Definately not a fun job. I had a PT come loose on me and get wrapped in the rear wheel...pulled the wires right out of the case.
I ended up cutting the case open and had to grind down the material that they use to coat the board so I could get to the wires and solder new ones to what was left of the old ones. I then re-coated the entire assembly glued the case back together.
I absolutely do NOT RECOMEND this. Frankly I'm amazed that it even still works, but so far it's been okay.
My suggestion is as above, get one of the new transponders that can clone your ID before risking killing it completely.