Removing Stubborn Set Screw???

On my 77' KZ1000A I'm trying to remove the small slotted set screw that holds the fork lock. It's frozen and have sprayed it several times with PB blaster to help loosen but not working. I don't have small enough impact driver bit to fit it. Any suggestions besides drilling the set screw? Is there a narrower impact driver bit I could find?

Maybe try heating the area around the screw with a propane torch,then cool it down with the pb blaster.

If you have a spare bit, why not grind it to what you need?

Don't have a spare bit. Does someone know a source where you can purchase narrower or smaller ones? Think I'll go down to Harbor Freight and purchase a propane torch.

Kano Kroil is supposed to be a really good penetrant.
Liquid Wrench penetrating spray lubricant is also good --- it did better than the pbb in a couple of tests. pbblaster has a catchier name & wam-pow label, though.

Red's outstrips (pun intended) every other bolt loosener out there......mix 50% Auto Trans Fluid and %50 Acetone and apply.....and Hey Presto :silly:

I read that recently on the internet seemingly to have great results. Worth a try and certainly a lot cheaper. Thanks !!!