cat 955l torque temp guage face turning grey and appears to suck in

I'm hoping someone can give me some ideas of what could be causing my torque converter temp guage to turn grey and with in 80 hours be completely grey where unable to read . I recently had trans rebuilt ,new hydraulic pump oil pump and trans cooler installed along with a new cat torque temp guage .after only 80 hours the new guage went completely grey . luckily it was still under warranty and cat exchanged it .installed second temp guage and exact same thing has happened.. anyone with any ideas of wjat could be causing this . thanks in advance travis