You have most likely damaged the key ways.
Check them for burrs and if burred take to them with a fine file.
Then a bit of lapping with some fine valve grinding paste till the whole contact faces is a dull grey.
Careless use of an impact wrench will shear the key, they respond much better to a slow tightening
Been awhile sense I worked on a Tecumseh but didn't they have a off set key in them? If so try putting the key the other way next time and try it, it might be timing kick back.
Been awhile sense I worked on a Tecumseh but didn't they have a off set key in them? If so try putting the key the other way next time and try it, it might be timing kick back.
also i pulled off the flywheel and the key did not shear this time, but it has a kickback like its out of time. so i pulled the pan and the crank gear and the other gear line up right on the marks. so iam at a loss as to why it is out of time.