Hello,I just installed the orig. speedometer in my 49 chevy truck and it worked the first day then quit.I checked the speedo and the cable and the drive gear and they all seem ok.However,I stuck my finger in the transmisson hole and found that I could slide the worm gear front to back and spin it on the shaft.Is this gear held in place by a key or a pin?What is involved in fixing it?Thanks for any help,Chip
