Thanks to info gathered here and the Simplicity site I find my Wards walking tractor is a Midland built 50A.
There is a lot of play in the right axle shaft, so much that the tire is rubbing slightly on the case. The oil seal retainer shows some wear. There don't seem to be any bearings for the axle to run on in the final drive housing. The key stock is crimped. Any suggestions for snugging this up?