Also a fan of the PB.
Evidence of it's goodness if found in the fact that it will eat not only styrofoam and paint, but your shop floor too.
FYI, don't get it on your skin.

I can understandn ot wanting to run out and buy a welder.
For a lot less $$, I'd dig around town and talk to a bunch of folks. I bet you could find a local welder who will bring a Ready Welder or something similar over to your house and do it for ya. It wouldn't be free, but would cost a lot less... it will take longer to turn on the gas and dial in the temp than to do teh work. If you have no other leads, call up your machininst where you'd take the head, and explain to him, and him if he knows a guy. My bet is he will.

Let me put it this way... this is teh kind of thing that if you were within 15 miles of me or any of my buddies, I (or one of them) would toss the little 110v in the truck and come do it for a few beers and a handshake. (but I'm no pro!)

You can always round up 2-3 car batteries, some jumper cables and a welding rod and have at it:
http://www.4crawler.com/4x4/CheapTricks/DualBatteries.shtml#Welding

EDM (electrical discharge machining) can remove any broken off bolt. Takes time, but it works. What they do with EDM is use a controlled electrical arc to vaporize the offending metal. It can be controlled to the point of even cutting new threads if the EDM head is right. Otherwise they just remove the core of the bold and then chase the threads clean.

Great ideas and info re:penetrating oils, EDM, etc. I rented a wire-feed welder, but it was only 135 amp, and though it would melt the end of the broken off bolt that I practiced on, I think the block acted like a heat sink; I couldn't get the nut to weld to the bolt stub sticking out of the block. Every time I tried, the nut would just twist off soon as I applied some torque. I had the truck towed in to a mechanic I know, and he, having a much juicer welder, was able to get a good weld. <img src="/forums/images/graemlins/cheers.gif" alt="" />