trailer question

The hitball catch mechanism can be adjusted from the botton (Hole where the ball goes)....If it is difficult to push down all the way or to pull up, You can loosen the nut below to get the play you need.........

That looks like an Atwood Hydraulic coupler. 6K...

http://www.atwoodmobile.com/chassis-components/hydraulic-surge-brakes.asp

I have one on my 20ft Crowline trailer and they can be finicky... The tab on top flips forward and releases the mechanism around the ball. If the trailer is sitting funny it may be difficult to release it.

Other than that, it is a great coupler. I have had my trailer since '02 and minimal problems.

If everything is working properly, you pull up on the tab in front
of the fluid resevoire. Stick your padlock or a bolt in the hole to hold the latch open. Then, when you lift the trailer with the wheel,
it shoudl release off the ball.

There is a mechanical spring inside, which sometimes breaks. My neighbors did so about 4 years ago. He's never fixed it. Just jumps up
and down on his bumper, after releasing the tab, and eventually the it comes off the ball.

I have the same setup. Replaced the whole unit last year for around $200. Mind was bolted to the trailer, so took about 15 minutes to replace. Looks like yours may be welded, so would take a little longer, but not much if you know what you are doing wiht a welder.

$200 was much less aggravating to me than dealing with rebuild kit on an
old assembly.

BKH

Since I see all that brake fluid rements- your brakes might not be working properly-- But the little slide switch on the right side of the actuator- before you back up- you slide it down to lock- so your brakes won't be applying as you back -up. But still you might need to grease up in there where the ball sits- lube it all around while your at it. Someone - the previous owner could've tightened the nut on the coupler- locking mechanism that goes over the ball. He could've adjusted it tight.