A while ago, I asked about my Felker saw problem. It is TM-75. The plastic roller developed a groove and finding replacement was a pain. I finally fixed it. 1/2″ repair coupling for copper pipe is almost the same size as the roller. I made a marker mark around the edge of the roller for about how much of the roller surface to remove so it will fit into the coupling. Using the side surface of the stationary grinder, I ground the roller until the mark was gone. The roller was not ground parallel, but one side just fit in and I firmly tapped it into the coupling. The coupling needs to be cut to the roller length or little shorter. This squeezed the roller so that it would not spin freely around the axle. I was able to grind out the hole with 5/16″ drill bit. 1/32″ bigger bit would have worked better but I didn’t have one.