I have a Mendota gas fireplace insert that is not properly functioning. Specifically, the pilot light will not stay lit after I have turned on the fireplace and run it for a while. However, the pilot stays on indefinitely if I don't turn on the burner. The thermocouple appears to be correctly positioned in the flame but beyond that observation, I am stuck. Having read other posts regarding the user unfriendliness of these gas inserts, I am reluctant to replace the thermocouple since I really don't know it that is the problem. Also, I have called the store from where I bought the insert several years ago and requested a service call to fix this problem. After being charged $175 for a service call lasting less than an hour and not having the problem fixed, I am not inclined to call them back. Any advice anyone can give me would be much appreciated.