Mcmaster carr has the washers. Type “torrington thrust” into the search function on their site.
Its been a while, but if I remember correctly, it is a 1/2” ID washer about .030” thick. Measure the thickness of the washer, have that amount removed from the intermediate drive gear wear surface, replace the block bushing.
Most gear wear happens when the bronze gear thrust surface/ bushing wear each other out. Once that happens, the gears are not meshing in the center as designed. The intermediate gear is low, and the gear mesh angles grind away at themselves.
The hardened steel washer prevents the similar metals from wearing, preventing all these problems. If