The keyer in my DC20B 20m QRP transceiver now works properly. Chuck Carpenter, W5USJ, read about the problem I and others had found with the keyer of the DCxxB QRP transceiver kits not playing back memories correctly, and sent me a Tiny 13 keyer chip that he had from an older kit to try out. I plugged it in to my DC20B and it now plays back memories perfectly. This would seem to suggest that there is a programming bug in the keyer chips supplied with the newer kits.
The list of problems experienced by purchasers of these kits is not encouraging: long waits for delivery, missing parts, replacements not forthcoming, sidetone much too loud, unpleasant noise burst between characters when sending, the keyer bug just mentioned, broadcast band breakthrough, and the TX frequency of the 20m kits being 1KHz too high. And as the designer has apparently gone backpacking, no "official" help with any of these issues appears to be available. Very disappointing.