:BangheadAllgood, some of my experience is just coming back to me.
With our JD 5425 ag tractor, it has the typical ag connectors with the round balls that you simply push in and jerk out to remove. I bought the tractor new, and from the start had a heck of a time connecting one of the hoses--of course, the primary coupling fitting. Everyone treated me like I was, well, just a stupid dentist that should know better than to fool with equipment. I got all sorts of advice: Let the loader down, release the tilt pressure on the loader bucket. Raise the 3 point. Lower the 3 point. Turn the tractor off and cycle all the hydraulic controls first one way and then the other (that won't work nowadays due to electro-hydraulics--you have to start the tractor to drop the 3-pt hitch.).
We had issues with connecting the 4-in-1 bucket to the Bobcat, too, sometimes whacking the fitting with a 6x6x18" block, or even a wood fence post. Then I met a guy who said, "Doc, that shouldn't be so hard." He took the flat-faced fitting off of another attachment, put on the combo bucket, and shazzam, even a weakling like me could easily connect the coupling, first time everytime, without any special efforts. We even figured out we could connect and disconnect without shutting the Bobcat down--just as easy as with it turned off via the "bleed hyd. pressure" switch. It was a defective/pesky flat faced coupling from the very start.
Huh. I wondered if the tractor fitting could be my problem. It didn't take but a minute to figure out that yes, it was the darn fitting. It never occurred to me that the fitting would be balky from the start--remember, we bought the tractor new. A year and a half into it, we changed the fitting and the problems went away. The tractor is the same as the 773. We don't have to shut it down to connect or disconnect (do lower your implement/attachment to release all or most of the pressure from those lines).
Two machines, two fittings, and all our coupling issues were resolved. It's worth checking. Doc