Just an observation, but is your equipment tray cracked/ broken? If it is not properly secured, when you tighten the main screw, one side of the back cap will not be tight. I have not had any leaks on mine. I also keep my "o" ring smeared with silicone o ring grease.
I have not had any roll over problems yet, ( I am adding the AA tower now) Are you running the stock "box" batteries, or are you running sets of nicads?
I wound up cutting the lead bar in half as it originally sunk as well. Keep as much lead, as low in the keel as possible, until you are happy with how it sits.
Get back to me and let me know how you are making out.