[Sam Mac]

OK first thing I'd do if it was my tractor is to pull the engine out, remove the tins and give it a good cleaning. Then you can check out the starter. They are a major PITA to get at in the tractor. Look at all the electrical connections. Make sure they are clean and tight. Cubs are notorious for crappy electrical issues. Battery on an 1872 is under the seat and they run the ground cable to the frame. I'd run a ground from the battery right to the engine block. You can try a quick and dirty test to see if you have a bad ground problem by taking a jumper cable, connect it to the negative terminal on the battery and the other end to the engine. If it spins over the way it should then you know you have a crappy ground. OK maybe I'd do this before pulling the engine. If that doesn't do the trick then go for pulling the engine. Easy way to do this is to remove the engine with the plate that it's bolted to. Six 3/8" bolts that you get at from under the tractor. Two of them are up over the top of the axle. Don't be surprised if you find a mouse condo under the engine sheet metal like this one had.