what does the set screw on the front sprocket of the primary belt due. What is internal on the front sprocket. I removed the set screw and then used an impact wrench to remove the nut on the front sprocket. Now I can´t get the disc to line up so I can replace the set screw, urgh! I am a brand new proud owner of an 81 FXB. I have worked on other HD´s (my 69flh) but I´ve never seen tis type of compensating sprocket.