Hey guys - thanks for your input. However, I don't think the original question is being answered. I believe my problem went from annoying to serious and is beyond the long beep now.
"While running the Seadoos, continue to emit a very long beep every 2-3 minutes."
1) The boats are not off, so the machine is not timing out and giving a beep.
2) In my case the lanyard connections always works perfectly with 2 beeps upon connection - never had an issue. Cleaned everything regardless.
3) A failed post sounds interesting; however, if the DESS/post is failing from partial disconnects one might expect the machine to shut down. The seadoo runs great while idling or at speed when the long beep occurs.
4) the frequency of the beep is very regular; i didn't personally time it, wishing i did for everyone's input
5) the other interesting point is the advanced diagnostics show the MPEM to report no errors