Small Engines (Lawn Mowers, etc.): Craftsman Automatic Transaxle locked up, craftsman model, automatic transaxle

Question
I just bought a Craftsman model 917271022 riding lawnmower from a neighbor that quit using it about 3 years ago. I cleaned out the carb and got it running but the trans is locked up. I tried to get it to go even into neutral but still locked up. I tried to "purge" the system but nothing. When you put it in gear it grinds both in forward and reverse. I figured it would loosen up when I got it running. Help

Answer
Did he say why he quit using it?   Grinding noises in any kind of transmission gear or hydro are not a good sign.

I would start by removing it from the tractor.  Put it in a  vice and see if you can manually turn it.  Look at what won't turn the input or the output shafts. If you are going to open up this hydro transmission be very careful and very observant.  Springs, detent balls, rollers, pistons, washers to name a few will come out too.  They have to go in where they came out.  

One idea, if you don't want to invest to much time and effort, replace it.  It should be available from Sears.  If you take to a dealer leave it in the tractor and take the whole unit in for an inspection.  Pay the inspection price and then compare,  Choose the best repair.  If it will cost less than 1/2 the price to replace the mower fix it.  If more than 1/2 replace it.  Good luck