Doesn't this motor have a main wiring harness plug back at the motor? If so unplug it, hook up your spark tester and jump the soloniod.
That should produce spark.
By the way....that tri hull weighs more than 500 lbs.
Everything looks ok....when it over rev'd did it sound like it was over revving?
Might have an electrical issue that made the tach read incorrectly and bog the motor down.
Somewhat guessing but it must be a dirty contact somewhere. Key being on is giving it more power and going down requires less amps than going up.
My motor the relay steals power from the hot side of the starter solenoid. Look at and clean all contacts including ground.
Weird one.
That about does it.....I usually get a long skinny brush and degrease/clean out the tilt tube.
When it's out of the tilt tube try it then....if still hard you will have to purchase a new cable.
Good luck.
