rear wheel drive locks up periodically when pulling it back.
If you haven't pulled the wheel clutches apart to clean, inspect and lube- now is the time to do so.
Wheel clutches? What number are they on the diagram?
On the drawing, see 9:4, which is a grease fitting. Have you ever greased the clutch pack? If not, you could try it and see if it breaks it loose. Just rock the mower back and forth and see it it frees up. If not, each side will have to be taken apart, cleaned, lubed and put back on. The greasing is supposed to be done every year. A small gun with low power is preferred, and a #1 grease would be good or a #2 in certain ones. I like the blue 'Nano' available at Wal Mart because it is a lighter grease that is very free-flowing. You only put in one shot on a regularly maintained clutch.
Cleaned all parts and used Lubriplate white grease. Seems a lot better, Thanks