In a quest for a mower with a bad engine so that I could swap a good running Briggs Quantum 190cc 6.75HP, I ended up with a TB200 w a Briggs EX625 motor for free that didn't run, the guy initially said he thought it was the carb but also said later that he hit a fence post and it died and wouldn't stay running after that, leading me to possibly believe the flywheel key may have partially sheared. At first I was just gonna swap the whole carb and fuel tank off my good running Craftsman M220 which is essentially the same exact mower just 6 years new and with a Craftsman badge instead of Troy-bilt. So I took the air filter off and man that thing was freaking filthy, and completely packed full, tried a cleaner air filter and that didn't make it keep running. Then the carb swap plan hit a snag when I sheared the governor linkage tab off the throttle shaft trying to remove the known good carb (oops) . So then I had to take apart the not known working carb and clean it, so I did that and got the mower running, but after a minute or so it started making noises, then I realized that I failed to check the oil level, when I took the dipstick out to wipe it off the oil that was on it was very black, then when I put the dipstick back in there wasn't enough oil, so I decided to change the oil with Mobil1 15W50 I had open, what came out was black and thick and not nearly enough usually it fills my 8x8 baking pan pretty full. But after that it ran fine, so I put it up for the night, and then after I put everything up, I remembered that I have a mower I picked up sitting around back that has a 300E with a bad rod or something on it, so in the morning I went and stole the throttle shaft from the 300E carb and put back together my M220 without having to buy another carb. Mowed the yard with it this morning, and the TB200 works good. My guess is the mower was running super choked down so bad since the air filter was clogged and whatever jet in the carb got blocked and when he hit something and wasn't making any real power so it just died and spared the blade and flywheel key. Now I've got yet another mower, and still haven't found a home for the Quantum.