I have a torque gauge in my 407 that is very "dim" for the first 10 minutes of a flight.  You can just barely make out the digital arc and the number readout.  After that it becomes as bright as the rest of the LED guages.  I'm guessing the guage needs repair, but if anyone else has had similar symptoms in their 407 gauges, let me know whether it was the sender unit or the gauge.  Greatly appreciated.  

usually when they go, they go pretty fast. generally no fix but core is worth $$. they are big bucks

It is well worth the $10,000. to replace the gauge.  The easiest way to a "check engine light" and over torque, is a dimly lit gauge. Don't try to skimp, you'll find yourself flying through a temperature inversion on a intensely sunny day while the gauge is washed out and unreadable. The subsequent engine inspection will just make the pilot look bad, if the light latches on. 

Just because it's readable in a dark hangar, doesn't make it readable in flight with the sun on your back.  Speaking from experience.