TOPIC: 1980 Mercury 7.5 hp flywheel

Hi, i have a 1980 7.5 that came with electric start which i wanted to take the electric start for another motor. the donor motor runs well so i was going to set it up with manual start to leave at my friend's camp. Here's my problem i had a flywheel that is stamped 236-3939 which is the same number as the one i removed. I installed that one and went to start it and it would not start, i put the original flywheel back on and it fired right up. I had another manual start flywheel same part number put that on no start, put the the original one back on and it fired right up. the only difference i see is the manual start , the red one has a space between the magnets, the grey one has no space. The grey flywheel is still on the motor so i couldn't show the magnet side. Any ideas?

I don't have either flywheel in front of me,...SO
Are the ignitions from the red flywheel's original motor the same ignition as the one under the gray flywheel?
Or,...Is the I.D. of the red magnets different that those of the gray flywheel.
Or,...Does the gray flywheel truly have magnets placed like the red flywheels?
doc

Thanks for the reply Doc, , i read somewhere online that switching the plug wires from one coil to the other coil had solved someones that had a similar issue. so i put the red flywheel on and swapped the wires and that did the trick! To answer your questions the flywheel came from the same type of ignitions, Both Flywheels are stamped 236-3939, and they both have the same magnets. My Question is this, how does the switchbox know which plug should be firing. on a car it would use the crankshaft position sensor, is it the trigger that does that? I am attaching a picture of the type stator assembly and trigger used on the motor. Thanks

i am attaching photos of the inside of the grey flywheel

Very interesting!!!
and,...Yes, the trigger senses when to "fire", but I still don't understand why switching plug wires resolved the problem? Cool though! I wonder if it is a "north", "south", magnetic pole position on the gray magnet compared to the red flywheel & flywheel key? Just pondering?
doc

Yup Probably the orientation of the trigger magnets in the flywheel. The red flywheel is from a 1976 7.5 and the grey is from a 1982 7.5, The ignitions are the same in both so i don't get why the flywheels would be different but it is running great now and i am going to go with that. Thanks