Rowe ami TI-1

I am working on a Rowe ami TI-1.
It has an intermittent problem in that records will select and play as normal but at random after some many records (no pattern to it)the jukebox will select' push out pin but the record basket won't move.
I can see the scan solenoid pushed against the microswitch but it should have energised after selection away from microswitch to enable basket to move. If I use a bit of force to bring solenoid back from the microswitch basket will start moving but don't want to overdo that
If I scan using the open-off-scan switch basket will move.
What would be causing the solenoid to fail intermittently. I presume microswitch is OK if basket will move with scan switch