Been running stove on low and only at nights now that warmer weather is here and today the stove stopped delivering pellets on 3 different occasions. It starts, fire ignites and then runs 15 minutes or so and then stops sending pellets. Emptied the ash drawer which was very full and have cleaned everything over last few days except baffles. I restarted it for the 4th time, this time set to medium and seems to be going fine. I read where there can be ash in behind the protective cover of the igniter but once the stove starts that shouldn't be an issue, should it? Any suggestions on what might be the problem?