Re: is working on a 55 fastwin diffiuclt?
gotcha! that little piece is called a flywheel key (a.k.a. a woodruff key). it is designed to be shorn to prevent damage to the motor's crank shaft. however, it can be damaged by improper flywheel nut torque as you described. if the the flywheel nut is not tightened down enough the flywheel will not be properly seated on the cam and will wobble, especially at higher rpm, and eventually shear the flywheel key. the flywheel can even "walk" its way up and off the cam if the nut should come all the way off. it can be dangerous to you and your motor. just imagine a solid metal frisbee flying your motor at the back of your head at 4500 rpm...not good. it's good that you caught it and would explain the sudden loss of spark. if the key is indeed broken, it is easy to fix with a proper replacement key which should be available at a Johnson/Evinrude dealership. just be sure that any bits of the broken, old key are removed from the magneto too. you don't want little bits of metal flying around under there. a broken key might also help explain some of the grinding sounds you described earlier and why the pull starter wasn't engaging the flywheel correctly. I would let them replace the key and torque the flywheel nut down to the proper spec. I don't know it off hand, but be sure to look it up and tell them if they don't know. once the key is replaced and the flywheel and pull starter are reinstalled properly, test for spark using your in-line tester or the spark plug on the motor trick. if you have spark, then try and fire her up, if no spark, dbl. check the gap on the points and make sure the spark plug wires are properly seated in the coils. sometimes they can wiggle loos and prevent a proper spark. Keep us posted.
BTW: in addition to getting a new replacement key and removing and old bits, make sure both the cam and the flywheel bore are clean, dry and free of any oil or residues. the flywheel is really just held on the cam by good 'ol friction and torque from the flywheel nut. if there's any oil on the cam it may slip and slide a bit and shear another key.