I have a St. Croix Pepin pellet stove and I'm having a difficult time getting the versa-grate to seat on the shaft. I can only get on side to fit onto the thru shaft...and it doesn't seem to move the way it should. I cleaned the stove yesterday and now am having a problem with too many unburned pellets sitting in the fire pot. I've also had a lot of 'clinkers' laying in the fire pot recently...more than I had when i first fired up the stove this fall...any ideas? I also changed to a softwood pellet at the same time...I wouldn't think that the change in pellets would make a difference. Any help would be appreciated.