Letting a printer sit idle can definitely cause the heads to clog up, as you've written.
But it sounds like it's more or less unclogged - but just more or less.

Is the print head in the cartridge, or in the printer ?

I'm wondering if there's still water in there, diluting things.
If and when you do a printer test page (which is usually in the printer's utilities, for alignment and nozzle check etc.) does it look ok ?
It could be that some of the nozzles are still clogged, but a test print page should be telling.

But the ink itself shouldn't get less black.
It has to come down to either dilution or a clogged printer head.

How much - how many pages - have you printed, and it still doesn't look rich black ?

You didn't mention the print head cleaning and test print routines; are you doing them? Do you get good colors, but poor severe missing grid marks for the black part? Do you know what I'm refering to? You might want to try using an eye dropper or something, to put some windex in the area where the print head rests for a day. That may clean up a partial clog.

The black grid/text zones are mostly empty when I print test page. I could scan test page and post it. My son gave me printer last yr. don't recall why he did? I think he does all his printing at work. The first text print had reddish text. This printer has 2 black ink cartridges. A big one for text and a small one. It does have a print head separate from the ink cartridges

It sounds like the print head is very much clogged up if a print test page doesn't have a correct print out. If the print head is in the printer, it's a bit more of a problem because you can't just correct the problem by putting in a new cartridge.

You'll have to run it through the cleaning procedures, and sometimes there are different cleaning routines varying from minimum to maximum.
I don't know that printer but there may be a way to put some wet paper towel over the print head to let it soak for a while, but that's just conjecture.

Also, I once bought some cleaning solution - which had some kind of light detergent in it - and you fill an empty cartridge with it and then run the cleaning cycles. I think I got it from

inksupply.com

I think they also have some instructions on how to clear a clogged print head.

seems my blacks are not printing at all? so perhaps the printer is using cyan/magenta/yellow to make text instead of using the black ink cartridges? the printer diagnostics say the magenta/yellow ink is going down, or being used and the blacks are both full. or not being used.

OK, the pigment black part of the head is completely clogged. kbarb has a good suggestion about the wet paper towel although it would sit on the bottom with the print head resting on it. Again, I would fill paper towel with windex and drop some windex in the area where the large black cart goes and let it sit for a day. Then I would run warm water over the head both top and bottom until ink stops appearing. When you did the hot water before, was it just for a moment/minute or more like an hour? Did lots of inks rinse out?

I think I would stay away from further use of the 'cleaning; or 'deep cleaning' routines until you let it soak for awhile. The Canons do a lot of cleaning anyway and you would probably risk a chance of making things worse. it is nice that the other parts of the head are not clogged.

Your printer uses the cli8 carts which are nice and large and hold more ink than newer printers, for the same price. It would be good to keep it running if possible.

The best thing to use on the printer or the cartridge is not water or glass cleaner but alcohol and a Qtip. never heard of using the others?

crap. printer is dead. i got the wrong printhead error message now. seems i ruined the printhead by cleaning it to excessively. anyone want a paperweight? it has new ink cartridges.

fixyourownprinter.com in the forum section has been covering Canon printers for more than a decade (probably two decades). Essentially aqueous ammonia has been used as a general solvent as a standard approach. Windex is such a product and includes some alcohol as well. A Q-tip is useful on the printer and the printer pads where the head sits in standby. I would think it would cause more damage than good if touched directly to the print head. In any case, it would be useful to look at the ink jet forum on fixyourownprinter. They cover canons more than others.

Just saw your message. I was going to suggest that you not put the head back before it was completely dry (like out in the sun for a few hours). Perhaps you got an error message for that reason. Perhaps you didn't drop the head back in just right. I would use some alcohol on the contacts of the head and the printer head holder and see if that resolves your issue. I have never damaged a head by running a small stream of warm water on the head slits and cartridge inlets.

is there no way to make the scanner function work with a bad printhead? of course i print out docs and than scan them to jpg format for emailing. works, but its crude. i dont have any other software for pdf/jpg conversion.

You should be able to use the scan function, but there's a much easier way to accomplish the "make pdf" functionality.

If you have a word processing program like LibreOffice (the more up-to-date version of OpenOffice), it has a convert-to-pdf function built in.

I think Word 2010 and later also has that functionality.
See :
How to Print Files as PDFs - using Word

Otherwise, you can install various convert-to-pdf utilities that emulate printers. When you want to convert, you go to Print, then choose the pdf utility (which looks like a printer option), and the end result will be a pdf document that you save on your hard drive - no printing involved.

Foxit Reader (Adobe Reader alternative) gives you a choice to install one of those utilities, and that's what I use)

See :

7 Best Tools To Print To PDF

Be careful to unclick the boxes for all the add-on crapware.

my printer is broke. dont matter if you have 23 print programs. i turn on printer. it stops at error message. there is no way to skip over error to scan

For getting around the printer error to do actual scans, I probably wouldn't know without being there, except to try scanning starting from the scan utility. My guess is you'll be blocked by the same error though. What is the error message - "wrong printhead" ?

But my suggestion wasn't about actual scanning. If all you want to do is make pdfs from word docs, it's easier to do it a different way without scanning. The quality will be better too.
That is, assuming you're starting from a word document, and not an actual piece of paper - for which of course, you would need to physically scan to get into digital form.

But for just creating a pdf from a digital word file, you can do either of two things :

1) Use the built-in functions of say, Libre Office or MS Word - OR -

2) Install a simulated printer (piece of software) who's purpose is to generate digital pdfs.
Then when you have a document open, just as with normal printing, you go to a drop down menu for "Print" or use Control + P.
When the print dialog box comes up, you choose a different printer - the pdf "simulated" printer.
For example, mine is called "Foxit Reader PDF Printer".

If all else fails in option #2, go into the Windows Printer settings and choose a different default printer - the simulated pdf printer - after you download it and install it of course.

These two solutions really have nothing to do with hardware or your broken printer.