1937 MCELROY MAC KEY. It was nearly impossible to miss this key when browsing eBay listing — probably the only Mac Key I’ve ever seen with a bright red finish.
What caught my eye (in addition to the red paint) was the fact it is a 1937 Mac Key, and not very commonly found on eBay. This key has the smaller civilian serial number plate, 
though it has “Property Of” on the left side and apparently the “U.S. Navy” was ground off.
I don’t recall hearing why Mac changed the damper on the 1937 models, but I have often wondered if it was due to the U.S. Navy contract (perhaps some requirement they wanted?). The cast iron “C” that makes up the cast part of the damper must have been rather fragile; this key and my other 1937 Mac Key both were repaired at some time in the past, with the cast damper breaking at the top in the thinnest part of the “C”. Tom French’s serial number list notes a couple of 1937 keys had the same problem — probably why it only lasted a single year.
Other than the damper, the rest of the key isn’t much different from the 1936 models that preceded it. The 1937 has the same dual pivots for the keying lever. The contact bar that 
linked the dot and dash changed in 1937 to remove the need for the cast mounting posts to support the contact bar at each end; instead, it mounted in the center.
According to Tom French’s website, the 1937 Mac Key had wire terminals on the base per the U.S. Navy contract. The Navy keys had a large nameplate that is very similar to those found on the 1938 and 1939 keys. To the best of my knowledge, there was no “deluxe” finish 1937 Mac Key. The civilian key I have has no circuit closer, though it appears the Navy keys may have. Judging from Tom’s list, there aren’t many of the actual ex-Navy keys in circulation.
I’m not sure I can remove the red paint without also removing the finish beneath the red paint. I may wind up just refinishing the key; I can’t stand the red paint (at least I’ll always be able to find it in the shack, hi hi).
First thing I plan to do is to replace the plexiglas paddes with the original styel finger knob and thumb piece. What to do with paint will come later. The problem with the red paint is that it went on thick, and there’s really no texture left showing in the original finish. Guess I can only try it, eh?
73 es CUL de KY4Z SK CL … dit dit …