Old and messed up Atwood Coupler

Last year I bought a 1996 Jayco popup trailer in very good condition and for a good price.   It needed a little cosmetic work on the inside.  Cushions and curtains, but otherwise it's solid and doesn't leak.  And the canvas is in good condition also.  I've towed it a few times and it looks like it has the Atwood hydraulic coupler with disc brakes.   I never bothered much with it because I packed the wheel bearings and it didn't have any brakes on it at all.   I am the third owner so I don't really know why it didn't have brakes on it.   Whether it was an option or the original owner choose to remove them, I don't know..   Whatever the reason, it's never been a problem and it has always towed great.   There were a few times that to unhitch it I'd have to  block its wheels and reverse the truck enough to get the coupler to unlatch tha ball.   I don't know much about couplers, and I really don't have a clue about hydraulic couplers.  

Thank you Jonny Quest for your reply.    After lots of research I think I have to agree.   This thing I suppose in its day was something special.  But right now I am thinking it's a POS.    

Thank you again for your reply.   I am looking at having this unit cut off and replaced.   Can you tell me what model bolt on surge unit you bought and where you got it?   You information has helped me tremendously.