Took the starter off and found it was sluggish. Tore it down and cleaned the brush plate in the ultra sonic. Cleaned the commutator and put it back together with some grease and the new gear.
Returned the amazon scratch and dent Oregon coil and ordered 2nd one. It worked great for about 10 minutes of mowing. Had to tow the tractor back to the shop with smiley. I was originally thinking the coil had died but in fact I did a poor job of installing it and a coil wire rubbed on the flywheel which cut it.
Ordered a 3rd coil which is a generic brand unit for $15 which is about $10 less than the Oregon units. It has one or 2 less core laminations (plates) but seems to work fine. Will know more when I use it a while but I expect it is AOK.
The new coil install went well. Buttoned it up and took it for a spin and the throttle cable broke off at the lever. I think I can shorten it and make a new Z bend. Pulled the wire out and it is clean with no rust. Going to shoot some graphite into the sheath then insert the wire.
Throttle repair finished with good results. Resistance of secondary on latest coil is over 5K which is the highest of the ones I have tested so far.