These Schaefer blocks are easy to fix. You can drill out the center pin from underneath and drive it out. Diameter of this pin is 3/16".
I made two new sheaves out of a 1/2" thick piece of UHMW. The center hole is 1/2" diameter and I put it on my wood lathe with an arbor. Then just turned the UHMW to the right diameter and turned in the groove for the rope
I made a new SS pin and drilled out the ends with a 1/8" drill and then just mushroomed the ends with a ball pen hammer.
Bye the way, Schaefer was of no help at all.