I have electric ceiling heat with individual room controls (Mears) with each dial being labeled 1-8. We usually keep our living room control set at 7. Last night my living room became very warm so I turned the control down to 5. It didn't get any cooler and my husband ended up turning it totally off before he went to bed. When we woke up this morning it was very warm in the room -- probably about 80 degrees. I decided to play with the control a little to see if I could hear the "ping" noise that usually happens when you turn a thermostat up. I did hear it, but not until I turned the control past 8 (the highest number). After I heard that noise I turned it all the way down again. It seems to have made a difference because the room is significantly cooler now, but obviously something isn't right. Is it likely that this is a controller issue? Can they be replaced? Is it a do-it-yourself kind of job? Any info would be appreciated.

I would replace the thermostat. It should have four wires two blacks and two reds. Always turn off the power at the breaker panel first.