Will it start w/o the air box on? With the carb inverted, does the float sit relatively level? It is easy not to get the seat not quite all the way in if you are not used to doing these- then the float level would be too low. But then again, I don't see where you had replaced the seat. Seat + carb cleaner = Bad. So do so if you haven't. Did you see the tiny hole in the brass plug on the LH side of the venturi? Inspect also the intake tube

Had to use a gear puller to get the flywheel off - it came off just fine. The (plastic) gear on the flywheel had been chewed off - there was about 3" of mostly intact teeth on it - not enough to catch enough to spin it to start though. That was problem #1. Shopped around on Saturday looking for a ring gear. No one had one in stock. Found a local guy who had spare parts from other mowers & found a used flywheel with an aluminum ring gear on it. Cleaned it up & got ready to put onto my mower & noticed something wasn't right with the crankshaft. I hadn't noticed when I pulled the flywheel off that the centering tip on the gear puller I used had wedged itself into the top of the crankshaft. It would turn freely, but would NOT come out. After several hours yesterday of trying everything else, I was able to drill through it & eventually pop it out. Miraculously, the crankshaft threads were not ruined. After that, was able to install the flywheel with the aluminum ring gear. Also on Saturday, looking at the starter more closely, there was a "burr" on the threads of the plastic clutch, I suppose where it wasn't being released & staying engaged with the flywheel earlier. I was able to take the starter & spin it by hand and was able to make the gear stick at the top every time. I bought (another) clutch kit, this time with a metal gear & replaced it. Unlike before, this time I took steel wool to the starter shaft & shined it, then used lithium grease on it the inside of it. Put everything back together & then shot WD40 on the outside of the gear. With this, the gear returns each time, not sticking like the previous one (so far). Before my original post, I had tried to crank the mower. I turned on the fuel shut off & tried to crank it & eventually gave up. I turned the fuel off when I stopped, but wasn't able to empty what was in the carb since I couldn't get it to start. (Since I had problems earlier, I put the shut off valve in. Other than this time, I never turn the mower off - I cut the fuel off & let it run out of fuel). Once I got things back together, I tried to crank the mower. As soon as I turned the shut off valve to ON & tried to crank it (would not fire), I heard the glug-glug-glug-glug of the crankcase filling with fuel. Sure enough, oil level was about 1/2" higher than what I knew it was before trying to start it last week. I haven't rebuilt the carb, but replaced the float & needle when it had this issue the first time. This was the 3rd or 4th time this has happened. It happened the first time earlier this year when I was trying to fix it up for use after it having had sat for several years. I'm not 100% sure, but the fuel tank (gravity fed to carb) looked really empty before I put gas in it before trying to start last week. I added about 1/2 tank of gas. I use Sta-Bil in it & the stored gas which is about 3-4 weeks old now (I purposely ran it low the last time I used it). I wouldn't have run the tank dry, so I'm assuming the shut off didn't do it's thing. In reading about some of these engines (mine is a Briggs & Stratton 12.5 HP I/C Quiet, model 28m707-0178-01), I see numerous reports of the same issue. Even though I see that a complete rebuild appears to address the problem, I'm not sure how that is ever more than one failed start or not allowing the carb to run dry to reoccur. I'm sure that the ethanol is the culprit, but haven't yet found a source for "real" unleaded gasoline. Is there a reliable solution for using gas with ethanol? Also, given my most recent self-induced repair, I'm not sure I want to touch the carb.... ;-)

It is likely that your "keep alive" battery is dying. This battery is on the motherboard per the preceding posts. Sometime the first indication of this failure is the date setting becomes in error. In the good old days of PC computing (about 15 years ago) you could get a replacement separate, larger CMOS/Clock battery pack that fastened inside the computer case and plugged onto the motherboard. Old motherboards had a connector for this. Typical battery life back then was 2 to 3 years. My experience with modern boards is the battery may last 2 to 5 years or more. There are a few cases of infant mortality where a battery fails before 6 months.

It's weird, some days I can just go and go and go, others, I just want to hole up with a good book or the internet. Today, I've been on the go since early--moved all the furniture (except the hutch and loveseat) out of the living room. Vacuumed, shampooed the rug. Took the shampooer apart to clean it (almost more work than the entire shampooing process). Did a couple of loads of wash, hung them out on the line, scoured the tub, took a shower. Now I'm just waiting for the floor to dry so I can give it a 'fluffing' vacuuming, and move the furniture back. Although, I did cheat and put on a clean pair of white socks at the door so I could come in here to use the computer--LOL! Tomorrow, I've got a bunch of paperwork to get done before a meeting I have to go to, and I want to make a basket of bacon appetizers for the gals since that recipe is in my next column, then there's the meeting at 5PM, and I have to pop in to see the managing editor for a project he and I are working on, so who knows what time I'll get home for dinner. And I know Thursday will be hectic--our dentist is an hour away. Our dental plan, for some reason, sends US the check rather than sending it to the dentist's office. So, since I hate to mail an endorsed check, we'll need to run up there and drop it off. So I figure I'll get up early and make them a nice fall spice cake with burnt butter frosting. Then DH and I will probably make a day of it--doing some shopping, going to lunch, visiting a bakery he's been missing since we moved. So by Friday.... I'll be wanting to stay in bed, too! Funny, DH has always been out of bed by 5:30-6:00, even on his days off. Now that he's 3 months into retirement, he's been getting up later and later--today it was 8:00!