Well, my second message to Unicomp did go through, but alas, the reply was not encouraging:
"Unfortunately, our current trackpoint module is not compatible with the M13 trackpoint.
I am sorry but we are unable to repair your keyboard.
Thank you for the inquiry and your interest in our keyboards."
I am perhaps fortunate (if a bit obsessive) with regard to these keyboards. Ever since I got my first one decades ago, I've found anything elsee nearly intolerable ergonically. The ThinkPad laptops are the next best thing, but newer ones lack the tactile feel of the M1. I think I have a total of four (4) or maybe five (5). Time for an inventory? So, no actual loss of function, given the spares. But I hate to see one go bad. These are somewhat scarce. I may have to sell the one w the broken TrackPoint. The keyboard itself remains good, and devotees of the "clicky" keyboards who prefer a mouse will gladly take it as-is.