Turns out the whole back of the air tank had broken off, in a nice round piece. Not the ideal thing to repair.Sorry about the lack of picture, I didn't think about it until after the fact. Anyhow, I went ahead, used plastic weld epoxy, and lined up the back as perfectly as possibly. Still leaked a bit on one side, though.
Turns out 1/2" to 1-1/2" PVC couplers fit nearly perfectly over the tank. I cut one down as best as I could (aka my hacksaw), and put it in place with quite healthy amounts of Permapoxy 5-minute plastic weld. You could probably get one to fit better, with better cutting tools, and cover most if not all of the back of the tank.
Now the tank is back in working order, although I'm not going to go beyond 3 pumps with the plugged stock pump. While it is reinforced and all, I prefer not to tempt fate. I also haven't looked into air tank size comparisons, to see whether this is a viable option for reinforcing different guns.
You will have to dremel out a few pieces of plastic on the inside in order for this to fit.
Edited by Buffdaddy, 22 June 2010 - 06:47 PM.