I had above symptoms on J Type, 9 years ago + not disengaging (always ok for first few miles or so). Solenoid, not clacking on a shake. Cleaned out and small o' rings replaced. I did use a bit of oil in the piston, rear area, thinking it would help for the future.
A couple of years ago, it started playing up. Went straight for solonoid, sure enough was not clacking, Did same again, though o'rings appeared fine. Didn't use any lube this time (I know it's a moving part!), my thinking that over time, oil may get sticky/dry due to the heat and stop it moving. Who knows?.