Northstar TS 1000 3 way frig. It's gotten hard to get lit. Lights with the piezio but won't stay lit when I let off the manual gas button. Problem seems to me that the flame is too small, not heating the thermocouple enough to activate it. Eventually it will stay lit after many tries. I thought maybe it was a plugged gas orifice. Took it off today. Orifice is clear and clean. I now suspect that what is happening is that the thermostat is stuck in the low position, keeping the flame very small. Problem has been occurring for over a year but I've been tolerating it. One time after turning the thermostat knob back and forth a few times, I could see a marked difference in the size of the flame thru the sight window and it stayed lit right away. Now it's gone back to its old habit of a small flame and difficulty getting lit. Anybody with insight as to how to solve the problem? Is there a way to force the thermostat to produce full gas flow? Is the problem in the thermostat sensor or the gas regulating system in the valve? Does the flame control mechanism in the gas valve get gummed up over time? Can it be cleaned or lubricated?