What was found
(CAN) WHILE ON A TRAINING FLIGHT AND DEMONTRATING AN EMERGENCY GEAR EXTENSION, THE GEAR WAS UNABLE TO BE RETRACTED AFTER EMERGENCY EXTENSION. THE A/C LANDED SAFELY AND WAS PULLED INTO THE HANGAR AND PLACED ON JACKS. MAINTENANCE FOUND THAT THE THICK CARPET PREVENTED THE HANDLE FROM RESETING THE BYPASS VALVE. THIS PREVENTED THE GEAR FROM RETRACTING. THE SYSTYEM WOULD WORK CORRECTLY ONLY AFTER FOECEFULLY PRESSING THE HANDLE INTO THE CARPET BEFORE ENGAGING THE STOW CLIP. THE CLEVIS WASADJUSTED SO THAT THE BYPASS VALVE RESETS BEFORE THE HANDLE REACHES THE CARPET AND STOW CLIP.