Originally Posted by stonny9
Kinda late reply but it sounds like the neutral/tow rod is moving out of position. There should be a rod/lever for each trans that you move to allow the mower to be moved with the engine off. Either it is missing a spring and/or the rod has an indentation to hold it and is bouncing out of the groove and moving. You usually have to lift the seat to see it.
I think this is a walk behind, no? Otherwise, if I have similar problems with my mower I will be checking those rod/levers!