Recently my heater blower has been failing. I get nothing from positions 1 & 2. I did think it was working correctly on 3 & 4 but the power seems to be getting less on those positions now. Can someone direct me towards what might be the cause of this. Initially I thought it must be the switch but I have done a little research and I see there is a resistor somewhere and it could be the motor itself. I am usually capable of replacing a part but my electrical knowledge is very limited so any help would be greatly appreciated.