Hi there, hope you are enjoying BYC!
Are you able to post a photo of your bator? Do you have eggs in it already?
My local friend who bought a cheap cruddy $20 bator.. ended up having to leave the lid propped ajar to get the correct temperature.
You might also be able to try a cooler location.. My very first bator wouldn't get warm enough in my cold house.. adding insulation worked.
3 degrees is the difference between life and death actually.. or at least it very well can be.. especially depending on which day of development. All kinds of deformities take place at incorrect temperatures.
Dial temp.. wafer thermostat? These things.. (parts) can go bad and also be replaced.. if parts are available..
https://incubatorwarehouse.com/egg-incubator-accessories/incubator-spare-parts.html
http://www.gqfmfg.com/replacement-parts/
Hope this helps.. and happy hatching!