Thanks, DeKay. I appreciate it. I do have some concern about the amp (one of the output tubes on that channel might be bad), so I'll probably have it looked at. Luckily, I have a replacement amp and speakers, so I can take a careful look at all of the possible causes. The power supply on that channel gave no indication that it was the problem; not sure how to check that out without risking the other driver. I guess I can put a meter on it to see if it's output corresponds to the front panel read-outs, but that won't give me any idea about an intermittent problem. Seems like I am spending quite a bit of time and $ on repairs these days. I guess that's a consequence of the bleeding edge, buying used and holding on to things.
To all- The Canadian distributor (Michael Tang) has said he will arrange for a return authorization to Feastrex in Japan. I'd also like to give a shout-out to Holger @ Voxativ in Germany. While inquiring about possible replacement full range drivers (I can't afford their field coils, but some of their more conventional drivers seem to be quite suitable), I mentioned my problem. He got back to me very quickly with information on their drivers AND also offered to see if they could fix the Feastrex. It looks like that won't be necessary, but his responsiveness and useful advice deserves mention.