Ran across a buy it now OD lockout switch on ebay a few weeks ago. The vendors price was close to $100 and the switch is not in that great a condition. Note the groove on the ball end where the typical wear occurs. No idea if the switch sold but anyone needing a new working switch may have issues with that one if they expect to mount it to the lockout cable bracket using the stock configuration of plate, lockwasher and switch. A worn switch can sometimes be given more life by removing the lockwasher but that is another topic and if it has already been done once then usually not much left to do except replace the switch.
As I've often said, no idea on how many NOS or good used switches are still around but I decided to see if something modern would work. Here is what I came up with using a modern microswitch based pushbutton switch. Good for 5 amps so plenty of capacity to operate the stock relays. This switch happened to be found locally but there are other brands that would probably work -- although they wouldn't necessarily have the same threads or dimensions..
The lockout bracket hole is a standard thread size so mount for the new switch was made by drilling and threading a stock 7/16-20 steel setscrew. The pushbutton switch I found has a threaded bezel with 1/4-40 threads. A 3/8 long setscrew was drilled using a #1 drill and threaded. The new hole leaves enough of the original hex opening in setscrew that an allen wrench can still be used if needed to fine tune the setscrew position. The new switch threads into the setscrew and height adjusted as needed. The pushbutton switch was made for a a screw in operator button. That was discarded and a 2-56 rounded head nylon screw took its place. At least that nylon screw can be replaced if it wears.
Soldered on some brass threaded inserts and encapsulated the new switch in plastic to resemble the old switch. If I were going to make any more would add a steel washer between the setscrew and switch and do the encapsulation differently but otherwise, it works. I had some stuff on hand so my total cost was about $5 and a couple of hours time. Anybody wanting to make one and having to buy some of the items would cost more -- but shouldn't be anywhere close to what seems to be wanted for originals.
Howard, That's fantastic! The reason I became a journeyman prototype machinist was for making parts for my Packards but work always got in the way so the only lasting thing I made was a mold for re-vulcanizing the driveshaft supports of the '48-'54 Henney-Packards. Nothing nearly as neat as this!