Trailer was built in in May '14. Sealed cord all the up to junction box inside of trailer. I did take a gander at both ends a couple hours ago and did use a small blade screwdriver as suggested. Cord just seems very sloppy in truck socket. All is okay with plug in box for 5th wheel. Sadly (CRS) I don't recall how the cord fit into bumper plug last year. Thanks for all your suggestions folks. Just maybe, it wouldn't hurt to replace the truck/bumper plug w/ same to see if that would help any. All else fails, would have an extra on hand for "X" reason.