Harman p61 running inconsistant

[kelly]

The stove runs fine for an hour or so just working away then it seems to ramp up, well I find the stove runs great and then it will ramp up a good flame and the auger will run for aprox, a minute delivering more fuel and the stove is set at stove setting and 3- 4- on the auger feed and room temp . I do notice it will bring itself back into check and give a few 10 sec auger feeds and then sort of get back to its perameters . I have noticed also on shut down it has shut the combustion blower off prematurely a couple times and the firebox was still holding embers , the combustion fan returns but it is becoming consistant to have this happen . it seems very similar to a ESP problem but is new , I did pull it and cleaned just to see condition . The venting for this stove is 2 feet horizontal with cap and Harman thimble with air intake . I don't usually run the stove for more than5-6 hours at a time since I am there just to perform some work and leave again . Your thoughts please all seals good and stove is clean