Toothpaste (can't remember which one at the moment) can be used on brass. And there are a few homemade brass cleaner recipes all over the net.

For the pits, can you take a dremel with a fine grinding drum and sand them out? That's what my father in-law did recently with some old brass wall sconces.

Last night on TV, Two ladies cleaned a old brass bed with ketchup.

I think that it is probably the acid vinegar and the salt in the ketchup that cleaned the brass.
You may try using a combination of salt and lemon juice or vinegar. Use a soft cloth, not steel wool, if it will do the trick.
I have an old brass lamp that I began cleaning with Brasso. I had to put it aside and I never finished cleaning it, but will try the salt and acid method next. I have used the salt and acid before with varying results, depending on the degree of cleaning needed. The solid brass is so heavy!
Funny, I was just thinking of getting it out and finishing the job when I read your post.

Brasso and elbow grease. It has worked for me on many old pieces. Salt and lemon juice works great for the copper pan bottoms - I never tried it on brass.

cut a lemon in half, and dip it in salt. Use the lemon as a "scrubber". Re-dip in salt as needed, and replace lemon half periodically. I have tried this on other metals, I imagine it would work on brass too.

I have a collection of brass candle stick holders, small electric lamp, and various other pieces. I use grapefruit and water. Fill sink with warm water, add 4 to 6 grapefruit, cut in half, and add brass pieces. Soak for 10 minutes, rub stubborn spots with grapefuit. Rinse and dry. Easy on the hands, muscles, eyes, nose, and TIME.

ok just to let you know, the lemon and salt does not work on brass...thanks anyways though.

hummm, are you sure you've got uncoated brass FoxRocks? I've been using lemon juice (fresh, not bottled) and salt for years. you just have to let the sucker soak a little.....i put the juice and salt in a spray bottle, shake very well, kinda dissolve all the salt i can and then spray. have to let it sit a little but it works....at least it does on mine. I would think the vinegar would work the same way. some of the newer brass stuff has a coating on it that 'protects' it from tarnishing; but it sometimes cracks and allows oxidation over time.

I dip a rag in vinegar (acid), then in salt, and scrub.

If there is laquer, you have to strip it off first.

Wash the brass with soapy water.
If the brass is simply dirty or oily, mix a mild detergent with warm water. Dip a soft cloth into the soapy water and wipe the piece down with the cloth.
Remove lacquer coating.
Polish the brass.
Reapply lacquer to the brass.
Wipe the brass off with a soft, dry cloth.

Here is a link that might be useful: http://www.perfectpicturelighting.com/antique-brass-lights-for-picture-frames.php