Remember when you spin it with a drill, how fast does the drill spin?
If you have a drill with one gear it only spins about 500RPM.
The OB idle about 750-800RPM.
Checking with a drill is not a sufficient check and why do you want to check the impeller!
The impeller needs to be changed every 3-5 years.
That power head is cooked, part out the rest of it and buy another good engine.
It is not worth the money to repair that power head.
If you have a drill with one gear it only spins about 500RPM.
The OB idle about 750-800RPM.
Checking with a drill is not a sufficient check and why do you want to check the impeller!
The impeller needs to be changed every 3-5 years.
That power head is cooked, part out the rest of it and buy another good engine.
It is not worth the money to repair that power head.