97 Merc Force 75hp won't start

Please help! My 97 merc Force 75 hp will not start... was good..always started since I bought the boat 4 years ago...run it once a month. Looked at voltage reg. Was burnt out...blotches of burn seen through amber plate. Replaced it. Still won't start. Starter engages flywheel but doesn't seem to crank it hard enough to turn it over. Goes...Whur....whur...then slower between intervals...whur.......whuuuuur. Starter pin with teeth does not drop back down..stays into flywheel??? New battery in March, but had it tested the other day..came out bad 114 CCA at tire shop mechanic, so took it (Marine Battery) back to Advanced Auto parts for replacement. They tested it at 468 CCA. Said it's good and will not replace. Who's right? Who's not? Could the problem be in the starter? Doesn't seem to be turning the flywheel strong enough. Gas is only a month old.

Any suggestions greatly appreciated!

Re: 97 Merc Force 75hp won't start

I had a similar problem with my 50 force. I had a bad starter. I would suggest you charge the battery completely first and try again before you pull the starter. The starter was my last resort luckaly it fixed that problem for me.