Remove the old mast and carefuly inspect the end of the track for signs of breakage. If you have a new mast compare the track lengths. If the old mast track is shorter, or shows signs of breakage, then you have a broken piece of track in the motor housing. This will keep the new mast from retracting and do exactly what you described. To repair this your have to remove the motor assembly, open the gearbox and remove the broken piece of track. While the motor is out and on your bench, take the oportunity to install the new track by winding it into the gearbox. Make sure that the track in the gearbox has plenty of grease, then replace the lid on the gearbox being carefull not to bind or pinch anything. Reinstall the motor assy and test for proper operation. Clearing the old broken piece of mast is absolutely required in order to make the antenna work. Hope this helps.
