A neighbor of mine retired and is moving to FL, he gave me his running AC 312 with a deck and tiller last Saturday!
Its in decent shape and has had a fairly easy life tilling a small garden and cutting less than half an acre of grass. The deck has a few rust spots but is useable, the tiller has new tines, new pulleys, and a new belt. The front tires are new, the rears are a bit eaten up from using chains.
The battery was weak, and about 5 years old, so I sprung for a new battery the other day. Keep in mind he's been using this thing regularly since it was new, and it started up in his shed and drove right into mine 5 days ago with no help starting. What I noticed is that is draws the battery down over a few days, there's about a 1 amp draw on the battery with the key off. I see wires coming from under the flywheel, so I'm assuming the alternator is under the flywheel, and there's an aluminum finned block right behind the motor. Not being very familiar with these, I'm not sure where to check first? Its got no lights, nothing but a starter and amperes gauge on the dash.
Is there one part that's more likely to be the culprit than the other? The wiring in general seems to be pretty clean, and it looks pretty much un-tampered with.
I called the original owner and he said he never really noticed a problem with it but he said he did keep a battery maintainer hooked up to it because it would go months without use at times. So that tells me it either had the problem for a while or he just never noticed it since he kept it plugged in.