1988 40 hp starter issues

[ashley13]

sooo one day my motor starts fine the next the starter spins but will not engage the flywheel so I replaced the starter. Still had the same problem. So I replaced the solenoid same problem but with a twist. Maybe one out of 20 attempts to start the starter will engage the flywheel but will barley move it but if I remove the plugs it will spin it like nobodys business. Oh and the battery is brand new and fully charged. Any ideas to what this problem is will be greatly appreciated.

[boats.net]

Check battery cables between battery and engine.