Set timer on dry. Turn start knob results in loud noise but no movement of drum. Belt OK and drum turns freely as well as motor shaft. What is cause?

SDtevee68 - Here are some usall causes:: #1- Broken or loose IDLER SPRING AND PULLY:: #1A- CHECK IDLER SPRING AND PULLY <REPLACE IF EITHER IS DEFECTIVE:::
#2- FAULTY MOTOR:: #2a- Check motor and
Repair or replace defective parts ;or the motor;; #3- DEFECTIVE SUPPORT ROLLER;;#3a- CHECK AND REPLACE IF FOUND DEFECTIVE :: #4- THESE ARE IF THE DRYER TURNS ON BUT DRUM DOES NOT TURN::
THESE BELOW ARE IF THE DRYER IS NOISY:: #1- NOISY IDLER PULLY:#1A- REPLACE THE IDLER PULLY:: #2- LOOSE BLOWER: #2A- TIGHTEN BLOWER TO MOTOR SHAFT:: #3- NOISY Support rollers;#3a-REPLACE SUPPORT ROLLERS:: #4-IF noise is
A high pitched whine,motor bearings may be
Worn;;#4A- Check motor bearings by operating the motor with the drum belt disengaged.IF motor does not turn easily and bearings cannot be lubricated ;REPLACE MOTOR OR TAKE TO A APPLIANCE REPAIRMAN TO MAYBE BE REPAIRED:: #5- BLOWER DUCT IS OBSTRUCTED_ #5A- REmove all obstructions and clean lint from the blower and blower duct;; ; I hope this helps you out ,if not holler back on this post
Have a good day and GOD BLESS::F.B.E.if IF