Hi, I have the detachable tow bar I got with car (assuming it’s the right oem one) Now can anyone give me help to how it fits on? Maybe it’s not been use in a while and all seized up .. The knurled dial doesn’t turn but the lock inset does with w screwdriver. Nothing visibly moves on tow bar. Also under the car is pretty rusty , electrics doesn’t seem to swing down, which I though they should. any help would be great .