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I am now having another problem. It is not keeping the programmed temperature. It changed the temperature from 76 degrees to 8 degrees and the time from AM to PM. I could not correct the temperature program using the ^ key. I could use the v key. Do you think it is time to replace the thermostat?

Old Maple/Chase Model 0988 (mercury switch) thermostat. How do I calibrate the temp swing? This model has a rotary dial inside with numbers from .4-- .5--- .6--- 1.0--- to 1.2 on the dial. Do the higher numbers create a greater temp/on-off variation?

Low battery light was flashing, changed batteries and now the display screen is blank.
How do I reset.

Low Battery light was flashing, put in new batteries. The display screen has not returned. I don't see a reset button.