I had the same problem with my combustion blower on my system. My problem was the motor bearings. I took the blower unit off and to an electrical shop and for around $50 he replaced the bearing (I think I picked up the bearings for about $24. You will probably have to change out the ignitor too at a cost of about $125..mine was almost shot and it comes with the new gaskets which you will need to change. I also took the burner out and cleaned at the same time. Everything went back together well and the system is working fine again. BTW I have changed out the circulating cartride a couple of times too...never the lower one only the one on top of the WH. Good Luck