I read enough bad prior to building my set that I avoided them and went with belt drive at 1 to 1. Your experience is matching about everyone else's. That being said Chinese rubber is mostly junk in my experience. Were I wanting to repair one I would check Lovejoy's web site and find out what material they use in their severe duty elements and then check McMaster Carr or Ebay for some stock andmake up a set,, and a set of spares.
I know,not much help,,,