This one doesn't seem to have been maintained at all
Tried to start it and the rope would pull at all. I removed the sparkplug and pulled and blew oil out the hole. Drained the oil and removed the intake and carb which were full of oil. The air filter was caked with oily sludge.
I bought a mower just like this a while back that was overfilled with oil and after I cleaned it out it ran great.
I cleaned the intake and carb and put the sparkplug in and it still doesn't want to pull. I'll have to look deeper. Stuck valve?
On the self propel the wheels and gears look good. Must be the belt or the tranny. I'm guessing the belt.