Re: Impeller change
I recommend you buy a J/E servie manual and a waterpump rebuild kit. Read the impeller change procedure in the service manual, while looking at the parts in the rebuild kit. After you are familar with the name of the parts and how they fit, Drop the gearcase and have at it.
J/E impeller changes require some aviation gasket sealer, some multi purpose grease and some permatex #2 non hardening sealer, to substitute for the OEM sealers and grease. Make sure you match them up correctly.
The aviation gasket sealer is used to glue the orings into the waterpump cover. The MP grease substitutes for the Triple Guard grease J/E recommends.