If the transmission has a growling/ buzzing noise when you try to move it, that means it has had a drive fluid loss more than likely, or the hydrostatic transmission has given out.
This machine being roughly 20 years old, maybe a low hour used one is available from a backlot at a large mower shop if you have such a shop still around your area.
There were a lot of these around, some still are. Others have simply been taken to the metal salvage and are long gone.