I need to remove the upper-left flipper bat on my bally Spy Hunter. However, one of the two hex bolts that holds the flipper bat shaft won't budge, and I've nearly completely stripped the head itself in trying.

Once I realized it wouldn't move, and I was damaging the hex head, I tried:
* Using a Hex allen wrench and once that was stripped the head too much, moved to a Star allen wrench, which also couldn't move it (and has now stripped the head down further)
* Using WD-40 (with the little straw nozzle, and paper towels surrounding it to avoid getting on other parts) to seep into the joint of the screw and loosen it. Didn't help.
* Hitting it (lightly) with a hammer (including using a screwdriver to direct the impact onto the hex screw directly) to loosen it. Didn't help.
* Tried using a lighter to heat the screw (after making sure to remove all WD-40 residue and keeping something nearby to smother any fire if I was wrong. Thankfully, it didn't catch fire). Didn't help.

At this point, any advice is welcome. This is my first time working on a flipper mechanism (though I have read several pages and watched some videos on them).

Otherwise, I see my options as:
(1) Just live it with. Put the other hex screw back in assuming it can tighten down the bat still. This makes the repair I was trying to make difficult (securing the coil stop correctly, which was attached very poorly with a single wood screw burrowed into the underside of the playfield)
(2) Drill out the hex bolt? Is there a particular type of drill bit to use? It would be tricky with the mechanism still attached to the playfield.
(3) Can the flipper bat be removed from the shaft at all? If so, I could just slide the shaft out from underneath, throw it out, and buy/use replacements. At least it would make drilling out the bolt easier.

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The first picture shows the flipper mechanism in question. The charring is from a lighter.

The second picture is for reference, showing a different flipper mechanism (upper-right flipper) with a presumably fine hex bolt in it.

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Thanks for the ideas everyone.

I don't have a pencil torch, the hex-head of the screw is too far stripped, and the hex bolt is flush with the surrounding metal, so I couldn't cut a slot in it.

I wish I would have thought of tightening it first to get it moving... forgot about that trick.

I think I'll go with cutting the plastic bat off, trying to slide it down (using the nut splitter to split it in half if necessary if it won't clear the bushing?), then drill out the hex screw on a vise. (Gives me an excuse to finally buy a vise). Hopefully the threads are intact in that bottom piece so that I can reuse it. (What is the piece called that attaches to the shaft and the spring and is moved by the plunger?). At least if I can get the plunger off, then I can make the game moderately playable until I can get replacement parts, because at the moment my wife and I are down to just Eight Ball, and as fast moving as that can be, it gets boring and frustrating after enough games (Its a drain monster for sure).

I think the flipper bat needed to be replaced anyway, because this particular flipper was taking a beating, being hit occasionally by the ball coming up from the lower playfield. I don't know if that's just how the design works, or if it was improperly adjusted in the first place, but I bet the shaft is ground down were the screws are supposed to secure it.

I'll post here on how it goes. If I remember, I'll take some pictures too.

On Saturday I was able to remove the flipper bat.

Things that did not work (Thanks for the suggestions though. They were all worth a try):
* CRC Freeze Out - May be some combination of the damaged hex head, or the fact that very little of the screw was exposed (and wasn't stuck due to rust), but it had no effect.
* Black and Decker Screw Removal tool - Maybe this one works if the part was secured in a vice and you really pound the tool in, but it never had any grip when I tried to thread it into the screw.
* Grabit screw removal tool - Just acted like a crappy drill bit, shredding the screw instead of digging-in and catching it.

I ended up just drilling the screw out. I was able to reasonably secure it with some vice grips, put a magnet next to the hole to catch the majority of the shards, and just kept drilling with a couple different bits I had available. The step drill bit worked the best. Of course the pawl was damaged in doing this too, so I have to find a new one of those.

That said, I'll admit that because I don't have any replacement on hand, I actually put the flipper and pawl back in until I receive replacements. I was able to do the original repair (better-secure the coil-stop instead of the single wood screw that was attaching it before), and the single hex screw secures the flipper enough for it to be playable. I'm not going going another week with just the one machine. (Which itself badly needs new flipper bats + shafts, because the shafts are so ground down by the screws that I cannot secure them completely and thus they are weak)

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picture #1 - Vice grips securing the pawl and a magnet on top to catch shards

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picture #2 - Magnet with a bunch of shards. This is probably 1/10 of the actual shard volume, as I cleaned it off many times.

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picture #3 - Plenty of the damage the shaft was from the drill bit, but I know now that some isn't, and that I should look to replace most or all of the flippers on both of my machines.
Unfortunately I couldn't get a good picture (on my phone) of the damage to the threads in the pawl.