Could be I suppose. I don't have or have worked on the BB machines, so couldn't really say. My experience is with caps and power supplies. I've found bad ps's to be the most likely culprit for strange or hard to determine errors or problems with devices. The other obvious thing is a bad ground or power connection. Wiggling wires will sometimes help show those problems. I think your error is more along the lines of, not working at power up, but, kind of works after. I'm not sure if you want to leave it on a while with the chattering reels, it might stop after some warm up time. I would be worried about excessive current draw messing it up worse, maybe. Clean power supplies (low ac ripple) and cooling are pretty important for electronic devices to work properly. I like to start with what could be the most likely fail point, then look at other things in a descending order of logical failure rates of devices. If that makes sense. Most likely to least likely. Sometimes it's a really strange failure but most are common failures.
Tony