Free Download All The Dumb Things … Trailer Coupling Lock Locks Free Download And can somebody explain to me how the coupler pin works to lock it in place? ... If you're having trouble locking the coupler, you need to adjust the shoe. ... Repacking the bearings would be a good thing to do with a new-to-you trailer. ... Sounds stupid, but I've seen people try to use a 1 7/8" ball with a 2" .... W..