Knob was cracked around shaft, so checked the identical knob on the temp switch - also cracked. When replacing temp knob, the switch just fell back into the panel. The panel has very lightweight, brittle plastic mounts for the switches. Thanks again, GE! I ordered the start switch and two knobs, then had to make another order for a new backsplash panel as I couldn't think of a way to do the repairs that didn't involve super glue and duct tape. The new knobs have additional reinforcement, but the backsplash has the same flimsy mounts and I will try to be extremely careful using the switches in the future.
With new backsplash, repairs were very easy to do, video explained it well. Shipping is a bit high but very fast. I ordered the backsplash on Dec 23 and it was delivered Christmas Eve.