Hey E
Those allens were originally installed with Locktite. Man, they really didn't want problems with that assembly coming apart. Two set screws; both with Locktite. Put more heat directed right at the allen heads. Use a propane torch. They will eventually break free.
PSPA has a used one in stock if needed. https://www.pinballspareparts.com.au/parts-by-machine/bally-parts/nba-fastbreak/fb-68.html
Wally