Quote Originally Posted by Demon View Post
After rereading your post, I wonder if the PIC could be damaged internally? Since you appear to have a heat gun, try applying a little heat just to the center of the PIC.

Is it possible that you abused the chip somehow, maybe a little too much current on a pin?

I've messed up PICs before by forgetting little things like current limitting resistors, short circuits mishandling test leads, etc. LOL The PIC would sometimes keep on working, but not reliably.

In some cases the damage would be limitted to just that port, everything else would work fine. They really are tough little buggers but there's only so much abuse they can handle from people like me.
I don't think it is the PIC but I've been wrong before - you only have to read this thread for examples

When using the soldering iron on just the oscillator pins I don't think there would be enough heat transfer through the tracks and PIC socket to have an effect on the PIC itself. By the way I'm using through hole components and not surface mount.

I've just replaced the OSC and everything now appears to be working, so either a bad solder joint as you suggested or the component itself. I'm going to try the OSC I removed in another circuit to see if I have the same problem.