it sounds like your second RHP, teh one that can only gets up to 74degrees broke. remove your animal from the enclosure, unplug the RHP from the t-stat and run it unregulated. if your t-stat can't get it warm enough at full power, can it get past 74 w/o? u can try that RBI suggested, but it's only like what an extra 6inches of suspension from your original probe placement but i think your RHP broke after 2weeks.
Ive unplugged the RHP from my thermostat and ran it unregulated and achieved a temp in the 80’s. Does this mean my RHP is defective when regulated or could it be my thermostat?