Our Roper (Whirlpool) Dryer RES7745RQ1 has two modes to dry; auto-sense and timed.

For years, we used auto-sense. Last week, we turned the knob to where we always do, The dryer kicked in and started drying, but the knob never moved, so the dryer stayed on until we turned it off. Thinking it was the timer, I replaced it. New timer does the same thing on auto-sense mode - never moves.

On Timed mode, it works properly - set the number of minutes, it dries clothes until the timer reaches the “Off” position. Obviously, problem is not not the timer assembly (so I most likely wasted money on that).

In searching online, I see most "auto-sensing" dryers have a moisture sensor somewhere in the drum area consisting of two metal bars sensing the change of resistance between wet and dry clothes. In looking in our dryer, I see no obvious sensor of that type, or even a place where it would go (if it fell off).

Also, don’t see one in the online dryer parts list manual - so how the heck does it sense “dryness” and move the timer? What do I need to troubleshoot next?