First of all, who's servicing your motor? If you're going back to the same shop again and again, you may not get your problem resolved.

You might give Al at Specialized Marine in Tacoma a call and explain your problem. He works on OMC products (exclusively, I think) and is very good. He's worked on mine for the past 20 years or so & I've always been satisfied.

... and no, I'm not related to Al laugh