dryer squeaking

People,

Dryer is maybe 20+ yrs old, but wish to keep it going. While it turns, there is a squeal/squeak that goes to the rythm of 1-2-3 and 4, then repeats.

I heard it could be either idler pulley, or rollers at bottom (if this model has them), or maybe even the belt. Do they have kits for such a squeak?

Thanks!