Mark-
I am so glad I found your thread! I installed two Betas with Seaprop 60s in my Leopard cat 2 years ago and my port SD has been doing EXACTLY the same thing as yours. I have accomplished ALL of the same factory "fixes" you have, including R&R, and continue to have the problem.
I recently ran a 3 day test comparing varying ATF levels at ambient and operating temps, in gear/out of gear, etc. (which all resulted in leaks) and have provided this data to factory (via Stan). He had told me the factory was going to use my returned original SD as a test bed. (He also told me I was the ONLY person reporting such a problem in the US...which I now know to be false after reading your thread).
In short, I have been unable to fully use my boat since I installed my new engines/SDs two years ago. I have incurred un-reimbursed yard costs to R&R the old/new SD (though they did come through quickly on the mechanic costs). I am currently waiting for a response from the factory (via Stan) regarding the next "fix." I'm beyond exasperated and now have reached the pissed off stage.
In the meantime, I am intrigued by your posted bailing wire/chewing gum fix. Could you PLEASE post a picture of the setup?
Many thanks.
Gregg Billman
SV Cruzan Rhumb II
2006 Leopard 40