I have an older Whirlpool Duet GAS dryer, model #GGW9200LQ0, it recently started stopped working. I opened it up, cleaned out everything (lots of lint). It testing, without the drum or belt installed, the motor spins and everything seemed to be working fine. So I replaced the rollers, idler pulley and drum belt as well as the thermal fuse and the foam seal at the blower fan housing.

I reassembled the dryer and it will startup. It is very noisy at first, like a dry bearing noise, but then it quiets down as warms up a bit. It produces heat and runs for a while but eventually it starts making a screeching sound and quits mid cycle.

I'd appreciate any assistance diagnosing this. I figure its probably the motor but want to see if there are other components to check first.

I have experienced this on a couple of dryers over the last year or two also. I repair about 100 a year. It is usually the motor bearings that are worn and / or starting to seize up. Once I was able to take the motor out and stand it up on end and squirt WD40 into the bearing area on each end. Once it was freed up I blew the WD 40 out of the motor windings and bearings and put some 3 in 1 oil in to the same area while rotating the shaft or the motor while holding the opposite item. This took quite a while and was kind of messy. It worked on one motor but on another one the bearings were too badly damaged and it still screeched when it was starting to turn the drum.
Another item to take a look at is the slipper plates in the front end that hold up the drum . They are part of the front cover support area. If these are worn out or missing the drum will screech as it tries to turn. It starts when the drum turns and never gets better however.

I agree. These bearings are not made to last by reoiling them as might be done on a large industrial electric motor. It would be a last resort to salvage a dryer that no longer had a replacement available.