Mechanical-timer models

Dryer runs and runs: timer won't advance or the cycle never ends

On mechanical-timer dryers, the timer motor advances differently by cycle. On Timed Dry it runs the whole time. On Auto/Sensor Dry it usually advances only while the heat is cycled off, so a dryer that never gets hot enough (weak or no heat, open element half, gas valve coils weak) can run forever on Auto while timed cycles end normally. Test Timed Dry first: that splits a heat problem from a timer problem.