Motorcycle Repair: 1976 harley flh speedometer removal, harley flh, wd40

Question
HI MIKE, I'M TRYING TO TAKE THE SPEEDO HEAD OFF THE CABLE ON MY 1976 FLH.  I PUT THIS ONE ON ABOUT A YEAR AGO. IT SEEMS THAT AS I TRY TO UNSCREW THE CABLE CONNECTION AT THE BACK OF THE SPEEDO HEAD, THE THREADED SIDE THAT ENTERS INTO THE BOTTOM OF THE SPEEDO ITSELF IS TURNING, SO I CANNOT GET THEM TO SEPARATE.  WILL I HAVE TO PULL OUT THE OTHER END OF THE CABLE THAT GOES INTO THE TRANNY?  IF SO, I'M NOT SURE HOW TO GO ABOUT THIS. THE ONLY INFO I SEE IN THE MANUAL IN THE TRANSMISSION SECTION  IS SIMPLY TO REMOVE THE CABLE (AND HOUSING?), BUT IIT DOES NOT TELL HOW TO DO THIS. CAN YOU GIVE ME SOME ADVICE ON HOW AND WHAT SHOULD I DO? ALSO WITH THE THREADED END OF THE SPEEDO HEAD TURNING AS IT IS, IS IT LIKELY THAT THE SPEEDOMETER WILL NOT WORK?
THANKS MIKE, CHRIS

Answer
If the whole thing is turning you have probably damaged the speedo. Even if you take the other end out of the tranny that will still not help you unscrewing the nut from the speedo. Try spraying some WD40 on the threads and see if that will loosen it up. If you need to remove the other end from the tranny it just screw in, like the speedo.
Good luck and happy riding
Mike