Ordered the dryer repair kit (Part Number 4392067 / AP3109602) consisting of replacement support rollers, idler pulley and belt. Watched the on-line video showing how to disassemble the dryer in order to make the repair.
There are a lot of 1/4" sheet metal screws holding the dryer together. As I removed each piece or panel from the dryer I used wide masking tape to tape the screws for that panel directly to the panel to avoid losing or misplacing them. Once I had the drum removed from the dryer I took the opportunity to vacuum out all the dust which had accumulated over the years.
Replacing the parts was straightforward. The most difficult part was re-threading the new belt onto the motor shaft and idler pulley. It can be done from the front of the dryer (as I was able to do), but I'd recommend taking off the rear panel.
Once everything was reassembled the squealing was gone.