I have a Johnson 120 (J120TLASB) that I am going to replace the waterpump kit (p/n 5001594). The instructions say to use adhesive 847 in some of the o-ring grooves and gasket sealing compound on the impeller cup and the impeller plate gasket. I have neither of these and the dealer did not say anything about these when I bought the kit. So are these sealers needed?