My buddies 05 Road king just started making a light squeal and it sounds like it is coming from the primary area. It happens when you run the RPM's up fairly high and then pull the clutch in to shift. It also happens when you run the RPM's up and then let off the throttle. Same light squeal that lasts about one second. I think it is the clutch slippping. he said he just had the clutch adjusted and primary oil changed. Syn 3 as he always uses. Any suggestions? Maybe readjust and different oil.