Re: impeller replace ?
Its very simple on that engine. 4 small bolts and remove the cover, pull out the old impeller. May have to use needle nose pliers to grab it. The key may or may not stay in place on the shaft so look for it. It has to be precisely square to the shaft or the new impeller won't fit or will push it to the back. Use plumbers grease on the new impeller blades and while rotating it in the normal direction (clockwise if I remember right) push it on then line it up with the key and push it home. Reinstall the cover with new gasket, torque the bolts and you're done.