I have a Brinsea Spot Check Thermometer. It's spot on.
It actually did go up to 97.4... but I'm thinking that's cuz it's getting warmer in the house.
http://www.randallburkey.com/images/1588_Instruction_Manual_2.pdf
http://www.gqfmfg.com/pdf/1588 WIDE RANGE ADJUSTMENT.pdf
These might help they tell you how to adjust temp.