I had problems with mice making a home in and around flywheel and magnets, nesting area getting jammed between coils and magnets. Does flywheel look like it is positioned on crankshaft correctly with key installed. Next, I would pull flywheel off and check if the coil heels are not hitting the magnets on flywheel, then check heels of armature plate to be in the correct position. I’ve had that problem more than once. Gene.

Apparently the motor has been sitting for awhile, that’s normal for compression to increase when you squirt oil into cylinders. It sounds like you found the problem. Not sure what the gas-oil mix is supposed to be, but find out and make sure you use quality oil and gas. Next I would take lower unit off and check or replace water pump, and make sure all passages are open to check for broken vanes jammed in there, then I would drain oil in lower unit and check for leaks, no more than 10psi, otherwise you could pop the seals. You can submerge lower unit in tub of water, if no leaks, and add oil, it’s ready to go. Then go to ignition and make sure everything is correct, using timing tool. Install motor in test tank, fire up, adjust carb in forward gear, and listen to that sound of a fine tuned engine running. Do you have a Johnson Service Manual for that model, if not, you need to get one, it will answer all your questions about adjusting all that pertains to that engine. I’ve seen some on this site that can be copied. Gene.