Manufacturers I know of making them:
Ushio #1003149
Halogen 1,000v 20A
Buhl #BE-QRG-22
Hot Restrike 1,000v Pulse Rated, 20A 350
I checked
Leviton, Bender/Wurth, Bryant, Osram, AAG Stucchi & Eagle none make a G-22
lampholder. Drexel, Morse, Glucksman and Etlin could be other manufacturers possibly making them I didn't check. Other manufacturers making lampholders I don't remember. ?PKI/Perkin Elmer possibly? GE used to but don't I think these days. Eiko might. Norman Lamps might.
Either above should work in the
fixture assuming the same seat height from the mounting plate to the center of the
filament. Many manufacturers like
Altman or Mole Richardson frequently have their own suppliers such as Zels, or ADR they buy a custom
OEM base from. Not to say it's not a universal
fitting but it can at times be different or slightly different in specification.
I was recently pricing out some replacement P-28s lampholders for a customer.
Altman no longer sells just the
lampholder, you have to buy the entire assembly for a
bit more money. Bryant and Ushio both make them but they were not as cheap as the entire
Altman assembly. Checked the Bryant price out
thru both my main lamp distributer and an electrical supply
house - both were about the same price at like $5.00 more than the entire P-28s assembly.
Sometimes you win, other times you don't be it getting cheaper - assuming the same basic item, other times you don't.
Give the Buhl and Ushio lampholders a shot - PA and just about any theater or lamp distributer can get them if not
stock as a special order. It assumes the same style as what you need and a better price however.