Check the balance of your props... mine are getting fixed now.... they will cause quite a vibration in the outdrive if they are out of balance (and shake the hell out of your outdrive).
No aftermarket anything on the boat.
I think I have found a couple of things... I think the boat will list starboard slightly at the dock. Mine was a little more because of water. I found that my cup holder under my throttle had no drain tube and was draining into the side of the hull.
Also...
I have a 2000 240DA. Similar Issue. After a good washing or heavy rain i get water in the back corner of my aft cabin in the starboard side. It happens even if the boat is covered... so it can't be from the deck or the cup holders etc.... I suspect the same issue/cause. Is it common to leak...
Ok--- still listing. It is a Dancer, not a deck.... I am a goof I know. I Found that the fuse for my tabs was blown... That will help when I'm underway... Still listing I the slip tho.... Where could water be? Listing quite a bit, a weigh 230lbs and when I stand port it's level. Thank you all...