Is it possible to repair/rebuild the torque sensing hub on rotor drive sheave? Pretty confident i'm starting to have some issues with mine on my early R52. When running wheat i plugged the rotor but the engine never slowed down so i didn't realize what was happening until i burnt the belt off. Anytime i've plugged the rotor in the past it would pull the engine down and stall it unless i hit the separator switch. Put on a new belt and finished wheat but plugged it a few more times without pulling the engine down, would maintain cylinder speed fine until you started pushing it a little and the rotor would stall. Went from running 3-4mph down to 1.5mph. 

It looked like the drive pulley might've been seeping a little so i did a full rebuild with new o-rings, guides, and pins and that all seems to be good now. Started beans this week and still acted the same. Cylinder speed around 750, get into a tough spot around 2.5mph and plugged the rotor without pulling the engine down. Noticed the rotor belt was a little loose as i unplugging the rotor as well. Talked to my local Gleaner dealers and they told me the hub isn't available anymore, and there isn't a parts breakdown from Agco so only option is a used one. I took their advice and pumped most of a tube of grease into the hub and ran the speed up and down, and after a few hours of cutting beans it seems to be working a lot better but still has me nervous.