Cleaned my Advance over the weekend, when I started the stove back up I notices a slight sound comings from the convection motor almost like a metal on metal sound ,it's hard to describe. sounds like when my bearings on my in-line skates get dirty makes that same sound. could it be dust, or are the bearings in the motor going, Second season with the stove burned about 5 tons that includes this season. any help will be appreciated.