help needed blower motor 450 sl (1977)
 

My blower motor is working intermittingly. Manual heat and air. The fan switch seems to lock in all positions and sometimes the fan goes on. No noise, works fine (when it works). I removed fan blower cover and sent some wd 40 into bearing area in center of unit. It seems that this could be a loose connectiion somewhere. I hear about a regulator, is there one on this model? I disconnected the firewall plug and sprayed with contact cleaner and reassembled. Same problem. I have heard that worn brushes can cause this problem? Any information apreciated. Abe G