1971 Johnson 125HP outboards Service Manual, Page 41Get this manual
DO NOT attempt any tests except those listed in the troubleshooting procedureDO NOT connect an electric tachometer unless it is type which has been approved for use with this systemDO NOT connect the system to any voltage source other than 12 volt negative groundDO NOT bench test this system without proper ground connections and these ground connections to be as short as possible
Figure 4-12Surface Gap Spark Plug
DISASSEMBLY OF DISTRIBUTOR
Remove flywheel as described in Section 5Remove statorSee Figure 4-14Lift off distributor cap, wave washer, and rotorSee Figure 4-15Remove sensor rotorSee Figure 4-16This will expose sensor assembly and anti-reverse mechanismSee Figure 4-11654