Steve Young "Might" be able or willing to tell you if that is an "off the shelf" part from Foremost Plastics. If they still have the mold, and they own it (as opposed to Gottlieb or B/W) then they can re-run you the part (min. run 1000).

If Steve has ever re-run the part, or wanted to and didn't want to pay for the min. run, he might be willing to go in on it with you for part of the run in various colors. They used to charge $50 for each color change as long as it used the same mold and was run at the same time. Therefore, you can combine the minimums (250 + 250 + 250 + 250).

More than likely, if the part appeared in multiple brands of games, then it was a generic off the shelf part that Foremost owned/created.

The problem with Foremost is somehow getting them to dig for or locate the mold if they still have it. If it is at Foremost, BAA or Marco may also be willing to go in with you if there is any need for the standard buttons and colors (no idea how many Gottlieb/Premier may have still had in stock when assets transfered to Gottlieb Devel. LLC).