FWIW, Just last week I picked up my rebuilt TR3 temperture guage from West Valley Instruments, in the San Pornando Valley here in SoCal. Moss has the particulars in their catalogs.
For $110, my gauge was looked at and cleaned, (worked fine), and I got a new capillary tube, sender, and gland nut. I'll be putting it back in, hopefully,in a couple of weeks. Exactly 1 week turnaround, and they had lots of assorted gauges. NFI
Best, Kevin Browne
'59TR3A #58370