Dryer stops when its on permanent cycle, but runs fine on regular cycle, I was told that a sensor is blocked with dirt build up. Why does it not affect the regular cycle. Tnks bill

The reason it does not happen on other cycles is that there are several sensors and on permanent press it checks the difference between two sensors, but on regular it only uses one. If you don't tear it down and clean it very soon the whole dryer will stop due to a burnout of the main safety, which is very expensive. Go to YouTube to see how to do this. You want to wash out all air handling ducts and parts as well as cleaning out blower fan and assembly. The lint is like a flammable concrete lining that will fill more than a five gallon bucket after two years.