You have stumbled onto a fairly common problem. Most (but interestingly, not all) folks who have commented on this issue have the same problem as you. It seems to go back many years. I have a 2008 2720 and the problem is still here. I am in the process of installing an adapter I purchased from Radio Shack that has 3 outlets and plan on wiring it into the TM 12V supply (probably via the radio circuit - Thanks Bill!). I had considered replacing the winegard socket, but it has some circuitry for the TV antenna system, and althought I don't use it at this stage, I might want it some day, so I decided to leave it as is and install the 3 outlet adapter along side of the current outlet. Here is a link to that discussion:
http://www.trailmanorowners.com/foru...ead.php?t=6887
You will note from comments in that link not everyone has the problem. I am not sure why, but maybe there are at least 2 types of windegard receptacles out there. Mine is so small it is all but impossible to fit any of my 12V plugs into it, even with extreme force. Hopefully my mod will be fairly simple and fix the problem once and for all.