I sent the Soundsmith SMMC20EN back a few days ago.  It was reworked a bit and returned to me last night.  I plugged it into my BG3404 (still haven't heard anything from the pro fixing my BG4002), and no sound out of the right channel again.  Thinking I'm just not making electrical contact in the right channel between the cartridge and the tonearm, I tried pulling the cartridge out a fraction of a millimeter.

And it worked.

Can you see the slight gap in the photograph?

The BG3404 turned out to be a great table to bring in off the bench while the BG4002 was at the shop.  Now that the BG4002 is back, I refitted the MMC20EN onto it and added her to the guest room system (on a little floating shelf I put together with pieces from IKEA).