does yours have the screws on this side? the left screw will be #1 screw. it is a fatter thermostat than standard. can you remove black plastic cover? sorry, bad pic.
do you have a picture of your thermostat? I have a different style than what is commonly shown on BYC.
we can go from there if yours is same as mine. I have mine set now to 3 degrees variance. It is very satisfying.