I just recently came into possession of a 1969 Johnson 85hp that had been sitting for at least 15 years. It had been stored inside and kept out of the elements thankfully. The motor will barely turn over with the spark plugs in. It turns over fine with the spark plugs out. I have tried replacing the starter as well as cleaning the spots where the starter is bolted to the engine to make sure it had a good ground. I have even tried bypassing the solenoid and connecting the battery straight to the starter. It still barely turns over with the spark plugs in. Oh and I have also tried multiple batteries. Any thoughts on what I should try next? Thanks!