pyrometer problems

[TURBOTREK]

I have an Ispro pyrometer (1-1500 degree) It is about a year old and has tracked temprature fine.I am noticing now that the needle appears to be sticking at various points. On long grades where the temp would have previously climbed to 11 or 1200,now it wont go past about 800. A tap on the gauge would result in the needle moving a bit higher but it doesn't seem right.I have checked the obvious, electrical connections, mounting etc. Anyone had a similar problem?

[Turbine Doc]

Check for chafed sender wire, also check tip of sensor if damaged it can cause reading error same also if sender wire is shorting out.