Quoted from Matesamo:There was no rubber cap on the plunger - standard ones are too loose and don’t quite reach the ball. The end of the plunger is threaded, is there a piece that is supposed to go there
The older Bally's used a smaller plunger tip. Not sure if he still has them on hand, but Steve at PBR had a few new old stock in his inventory about 2 months back. Or tape wrap the threaded end and use the newer style if need be.