1971 Johnson 125HP outboards Service Manual, Page 42Get this manual
Figure 4-16Removing Sensor Rotor
Figure 4-17Leakage Test on Distributor Cap, Rotor, and High Tension Leads
units have provisions for checking most functions of the ignition systemSee Figure 4-27BDetailed instructions for the use of any tester are provided with the unit; therefore, only gene-ral information is given here See Section 2LEAKAGE TESTING The distributor cap, rotor, and spark plug high tension leads may be tested for leakage or insulation failures by using the ignition analyzer and standard ignition coilConnect the coil to the ignition analyzer as for the coil testConnect separate test lead with suitable clips to the secondary terminal of the coil (by-pass the MA-12 resistor adapter when using the Stevens Model MA- 75 ignition analyzer) and to the conductor of the component being tested (lead terminals on distributor cap, rotor arm, spark plug high tension lead)Probe the entire insulated surface of the component being tested with the grounded test probeSee Figure 4-17Arcing will be apparent wherever the insulation has broken down, due to moisture or carbon trailsDISTRIBUTION CHAMBER