It's been since April and Moogfest that I've been trying to replace a defective keyboard switch on the Werkstatt. Phone calls and emails and a posting in this forum all went unanswered. Good news - I have been able to identify the part used and replace same successfully. This switch was intermittent from day one. After much searching from parts houses, comparing footprints, pushbutton shaft sizes, height, above circuit board, and activation pressure, the switches used for the keyboard are
the ALPS SKHHCWA010 tactile switch.
These are available though Mouser electronics, and possibly Newark and others.
As a nod to the retail store, I did make a recent purchase and submitted a request for a replacement switch to be included with new products being ordered. They were good enough to misread the request and ship one of the plastic button covers, but not the switch itself. So, despite the misread, I have to give credit to Moog Music store for being the first to acknowledge my search for parts. This has been a little frustrating, but the technical problem is solved now. I hope this information is useful if anyone else has keyboard switch problems.
Perhaps because this Werkstatt was built in the class during Moogfest it didn't include the usual support (read paperwork) to allow it to be under warranty, but I have found no successful way to communicate to Moog Music about this synth.
Again, the technical part of the problem is now happily solved.