The feed motor/plate is pretty simple. As such, it can be affected by build up of fines etc. A good cleaning of the plate is
a big deal for performance. Also, the arm/wheel alignment is a big deal too. Clean those areas up, and the performance will
change. My Pioneer got some build up after burning "tons" of wet coal. Took a higher and higher feed rate to achieve full grate
burn. After cleaning plate, slide, etc, maximum burn was achieved at 38-40 vs 50-52 when gritty. Stove is pumping away
right now, the oil burner nice and quiet!