by nvmos2 » Tue Jan 28, 2020 1:45 pm
First, realize that, over time, mechanisms are often changed from one case to another since the mechanisms are interchangeable, so the mech in your vest pocket may not be the one that originally was produced with your case. (Unless of course you have one of the few survivors that has the serial number mech sticker still readable and it matches the plate on the bottom of the case.)
Also, the Plus mechanism paid out the standard 20; the Plus JP was paid by operator.
The VP has a long history; first produced in 1938 and made by Mills, and others including SEGA past 1959. Chrome versions started in 1940; clearly there were fewer of them due to cost, war-time restrictions, and it's bright and noticeable (part of the idea behind the VP was that it was inconspicuous and easily hidden under the counter). Judging from the serial number lists, the surviving VPs indicate approx 1 out of 30 are Chrome.
The JP Register was standard with the models that had Plus reward plates. It was not standard on non-Plus models, but that does not mean that it could not be added, especially when others started making/revamping VPs; Abco Novelty in 1947; Friedman Amusement in 1950, etc. Sega lists a JP meter in their Mini-Sega parts list (1959).
You will find The Coin Slot Guide 13, Guide to the Mills VP, very helpful with your new machine.