As a general rule a picture of a problem is a big help.
In this instance a bit hard if its all pulled down allready.
Theory with a motorbike is that you replace the chain and sprockets together.
Given that, is there room to mount a new sprocket on the same side of both sprockets. Step both across the width of the sprocket.
Either bolt or weld them in place.
You do not need the same pitch chain and tooth count. You can use anything so long as the ratio is the same.
Its a ride on mower, not a race car.
Cheers, Bob.
