GREENWOOD 200 DAMPER DOOR BUILDUP

I HAVE A GW200 THAT ITS IN ITS 3RD SEASON. I HAD MAJOR PROBLEMS 1ST SEASON. INSTALLER HOOKED UP INCORRECTLY AND WAS HAVING MAJOR CONDINSATION COMING OUT BOTTOM AND EVENTUALLY I HAD A CHIMNEY FIRE! I WAS IN CONTACT WITH HIM THE WHOLE TIME AND HE ASSURED ME THAT IT WOULD GO AWAY. FOUND OUT A VALVE WAS OPEN TO MUCH SEEMED TO CURE PROBLEM. I NOW SLEEP WITH 1 EYE OPEN WHEN BOILER IS RUNNING
I WOULD LIKE TO KNOW IF ANYONE HAS A CURE FOR THE BUILDUP OF THE BLACK TAR IN THE DAMPER DOOR ON WARMER DAYS. I TRY TO LIMIT THE USE ON THESE DAYS BUT SOMETIMES WE ARE REAL COLD AT NIGHT AND WARM DURRING THE DAYS.
I WOULD LIKE TO KNOW IF THERE IS ANYONE IN CENTRAL NY THAT CAN SERVICE THIS BOILER. I WOULD LIKE TO OPEN IT UP AND INSPECT MAKE SURE THERE ARE NO PROBLEMS INSIDE.

THANKS FOR ANY HELP.