Switch Assembly

Be sure there is continuity between terminals S and M, and between terminal S and ground. Use a circuit tester (set in "ohm").

Also check to be sure there is no continuity between terminal M and B.

Terminal / Specified resistance: 

1. S - M / Continuity
2. S - Ground / Continuity
3. M - B / No continuity

Fig 1: Checking Continuity Between Terminals S & M