On our Whirlpool electric dryer the plastic pulley "guard" that sits on the shaft of the dryer motor melted and wonder what it does and how to replace it as it seems to be part of the Pulley-Mtr Part Number: AP4510074
Have replaced the belt after it broke last month and it worked for four loads then the belt broke again. Didn't notice the melted plastic part as it had come off from whether it was and over to the right rear of the chassis.
any help would be appreciated.

Also we have the older all metal idler pulley is the new one with the plastic wheel a better option.

thanks
herrbutzie