I am having a issue with my Herpstat 1. It will not hold a steady temp for longer than a week.

I set the temp to 93 and gives my tubs 90. A few days later it's still set at 93 but the inside of the tub is 86. So I bump it up till the inside reads again 90 +/-, usually the herpstat reads around 96. Everything is fine, then a week goes by and the temp in the tub drops again to 86 +/-.. Anyways you get the point. It's been doing this for the last few months. I am thinking the probe maybe is going out? I finally gave up & am just using my VE-200 again since at least it's consistent.

The probe was attached to the top of the flexwatt using tape.