I remember one failing, It disengaged in the middle of a job, would not re-engage, It was on a 1978 SteamVac Ol Blue 1 ton 14ft box van that Claude had when I went to work for him. I finished the Job by inserting a 3/8 bolt into a threaded hole which secured the clutch to the shaft. The newer clutches don't have this feature. Upon dissassembly I found the power supply wire had rubbed thruogh and grounded out which popped the fuse.