Dryer runs with heat when the start button is depressed and held down. When start button is released the dryer comes to an immediate stop. Which part is likely bad? Thanks for any help 
The centrifugal switch on your motor is not working. It might not be switching on due to a little arm that triggers the switch. Or there may be a clog or lint preventing it from switching on.
It may be the contacts inside the switch are burnt / corroded.
It is possible to check for the reason.
Watch Bill show you the idea in this video.
https://www.youtube.com/watch?v=CaaqRXQERVc
Likely the motor will need to be replaced. Here’s your part.
http://www.appliancepartspros.com/ge-kit-motor-and-we17x22217-ap5958529.html
ogroup85 said:
Dryer runs with heat when the start button is depressed and held down. When start button is released the dryer comes to an immediate stop. Which part is likely bad? Thanks for any help
Thank you for the answer and link. I have ordered a new motor and will see if that corrects my problem.