Just to complete the record here:
Today I picked up my fully operational MR27024. Testing it, I have it working in one room with only its own whip antenna, and it seems to be as good as my other MR27024 in another room with an outdoor wire attached.
It took the shop nearly two months to get it all fixed. In putting it back together two weeks ago, the technician did something that kept the left-most bank of front buttons from operating. That's all corrected now.
I don't mind that they had so much trouble getting it working. It's a two-brothers-outfit and it must be the most peculiar model of radio they've ever had in their shop. I was pleased to be able to turn it on in their shop today and (just with the whip antenna) pick up a perfect signal of AIR's DRM to show them what it does. The brother I was dealing with was impressed.