HELP!! Stuck allen head screw in biscuit joiner

[AJ Roadster NJ]

I have a Porter Cable biscuit joiner. I've changed blades between the normal and FF (faceframe, tiny) blade maybe 20 or so times in the three years I've had it.

Yesterday I cut some FF holes, then changed blades as usual, just snugging the 5/32" allen head screw that holds the blade, and then cut 130 larger (#20) holes in a row.

I think cutting that many holes at one shot really torqued the thing down, now it WILL NOT BUDGE. I have to get the FF blade back in to finish my project.

I leaned into the 5/32" allen wrench that came with the joiner and twisted it about 70° or so. No problem, I say to myself, and go get the allen sockets out of the drawer, mount the right one on a 3/8" drive ratchet (no breaker, just the normal ratchet) and instantly broke the wrench off in the bolt.

So I dabbed some solvent on it and let it sit overnight. Today I went to Home Depot and bought the Rigid "guaranteed for life" allen set and, right away, twisted that bad boy up too.

What should I try next? Heat? Will I ruin the joiner if I apply heat, and if not, how do I get as specific as I need to be with that one little mounting screw? I don't want to destroy the blade's temper.

Any help appreciated...

AJ