I was wondering if anyone had any suggestions....today was the 1st time I hitched up my Dakota I bought last year. Everything went great until the coupler sleeve wouldn't go all the way forward to lock. It almost seems like the ball is too big, which it's not (2 5/16 as printed on the ball and coupler). I tried pulling forward and back a little and jumped up and down on the tailgate....kicked it...the couple arm (?) just doesn't close all the way to allow the sleeve to come forward.??? Don't know if it was this way when I bought it because I didn't really know about hitching last year. Is this defective or am I missing something???

Something is blocking the locking plate from closing or blocking the sleeve from moving up.

Unhitch the trailer and look inside the ball recess... Nothing there, good, then move the locking plate (you called it the coupling arm)closed. If it won't swing closed, check that the pivot bolt is secure and nothing is bent. A bit of oil on the pivot is good maintenance.

Now that the locking plate is okay, try to move the locking sleeve in to place. again check for bent parts and oil the moving ones.

Everything work now ?? Try to hitch the trailer again.

Let us know what you found ...

One more thing... The truck/trailer hitch should be about level with each other. If there is a significant height difference. the back edge of the ball draw bar may be in the way of the locking plate.

Thanks for your reply. I came to the conclusion today, in a round-about-sorta-way, that the problem is indeed that the trailer is not level. I noticed this yesterday but didn't put 2 and 2 together that this can be solved by either flipping the ball mount or getting a different one. The trailer dealer flipped the ball mount I had on their "up" when he swapped the 2" ball for the 2 5/16" ball I'm using now. Not sure if I flip it back if it will be the right height. Any tips for making sure I have the ball the right height? Also, I don't have any tools/wrenches to remove the ball....what do I need to do it? Might as well buy some to have on hand.....
Now my next problem...for some reason now the lights don't work....the plug is kind of funky so I'll fiddle with it more tomorrow. (one problem at a time!) Thanks!