Pilot won't stay lit - Vermont Castings Radiance 2560

I have a 16 year old Vermont Castings gas log stove and I can't get the pilot to stay lit. I can get the piezo to fire and the flame to catch. But if I let go of that gas knob, no matter how long I hold it down, the flame will go out. I replaced the thermocouple in case that was it, but it didn't help. I have also adjusted the screw that is supposed to adjust the size of the pilot flame, but it doesn't seem to make any difference. I can tell that the flame is too small. It does not reach all the way to the thermopile or the thermocouple. I have tried to blow out the pilot hood with compressed air and have tried to get a small wire down there (but it's really hard to get in there) just in case there is any blockage. So far, no luck.

Every year this thing has been a bear to get lit but this year I can't get it going at all.

Any other recommendations, or is it time to call in a pro? Thanks for your help

Hey Bob - it's a Direct Vent. Vents out the wall, about ~3-
4 feet above the top of the stove.

Trying this again .... posted a reply but it disappeared...

Sounds like it could be a pressure issue I guess but not sure what would have changed to cause it. It's liquid propane, 3 100 gallon tanks ganged together to make 1 virtual 300 gallon tank. The gas line run to the VC is about 25 feet at most.

I do have the old thermocouple. I get putting a flame to it and I do have a multimeter, but how should I use it to test the thermocouple?

I checked the old T-C with my multi-meter. I don't know how to use this thing well enough to be completely sure of my results though. I *think* what I got was no reading at all on AC voltage, no matter where I put the dial. On DC voltage, I did get readings, and best I can tell it would settle in around 18. It would jump wildly all over the place but if it settled in it was around 18. So maybe it's reading 18 mV?

Anyway, seems like it's possible there's a pressure issue so I'm going to get the gas company in to take a look and see about getting it going. Thanks for all your help and Merry Christmas.

Just to tell you the end of the story... had the gas company out, and the gas pressure was fine. The thing where the gas comes out (technical term) needed to be cleaned. Now I know, for the next time. I did the compressed air thing, but it needed to be taken out and physically cleaned out. Working great now.