The plug in my Midi gets loose too, it's not really bad but the sander will cut off every now and then and I have to push it back in.
Do a search on it, I think there are some instructions around on how to tighten the plug without replacing it. I did it on the loaner I had while I was waiting for mine to come in. It's not rocket science though, if I am remembering right you just need a screwdriver and 5 minutes or so to fix it...
If mine gets worse I will have to do the same thing to it...
-Jim