Thanks dirtybird.
I just received a new IGN module from RCexl and installed it on the Skybolt - guess what!! Everything seems to work perfectly - just as before. I am elated! I will now install the cowl and go to the field and see if everything is still OK after a complete assembly and run-up.
If all is good - it begs the question - can a defective Kill Switch damage an IGN module? In particular, is the RCexl "OPTO" kill switch really any good since both mine appear to have failed? I took one apart and all wires are soldered to the same little PC board. I see no sign of an "optical" separation between the battery junction and the RCVR junction - check out Smart Fly for a real optical separation! Guess as suggested by acerc, I'll probably get the Smart Fly and have complete noise separation IGN to RCVR.

So does anyone know if this RCexl kill switch could damage my IGN modules??