The cover of the thermostat fell off when someone brushed by it too hard. now it wont read correctly....the needle is always quivering and the mercury cylinder on the inside is tilted to the right and that is where the mercury sits...to the far right. i have the heat at 15-17 but it reads 20 +. Will this affecting my heat bill or heating in general? How do I get it fixed if so? I appreciate any information you can give me. Thanks.