An update to this old mower. The key provided was too short only half as long as the key way. It would allow the electric clutch key to possibly rise and leave the clutch and occupy the unused space in the pulley.
Highly unlikely but possible. I replaced both keys with a single key. We are good to go.
The install is done and all is well. I'm getting 3200+ no-load RPM and it sounds quieter than the 18HP it replaced. Maybe the 18HP was a faster RPM engine? I cannot find the no-load spec for it an Intek 407777– 0128- E1. I would love to see it.