Hum Feedback Problem Seeburg 100 JL

I'm experiencing some very unusual feedback through the speakers, volume spikes for a split second with loud feedback when I hit the cancel button on the back of the cabinet. loud pop when tone arm first lands on the record, louder pop as it comes off the end of the record, then on the final selection played there is a loud low pitched Hum when the last record cancels, Hum decreases as the record is placed halfway back into the record magazine slot. There is no Hum during record play, other than the above issues amp has great volume and has been recently recapped, pulled the 3 prong mute plug seems to make no difference with the symptoms.

Forgot to mention the amp is an HFMA1-L6