The only 2 problems I have had is with the muffler rotting away and the associated weak mounting of the muffler to the to the engine. I bought a new muffler and had to put oversize screws in the mounting holes.
The other problem I had was the needle valve in the carb. went bad and it caused gas to leak in the cylinder. The mower would not start until I blew the gas out of the cylinder.
I have had numerous riding mowers made by many different manufacturers and I know this is the easiest to drive and use out of all of them.