helpful info on resistor keys
 

I have found that the best thing to do when your key won't work is use small amounts of contact cleaner on the connections. Or if you are cheap (like me) just simply rub the contacks with a pencil eraser. Didn't know if anyone needed that but it saved me $95.00
Rodney

Doing the same with the ignition switch itself can be helpful too. Clean the actual contacts that mate with the pellet.