That makes sense.
When the swage failed on the D2, I had a hell of a time getting the quick release off(which obviously was still on ... minus hose tho). That was passenger side.
Drivers side took some effort to remove, but came off with small effort.
Armed with both new hoses tho, they went on with a satisfactory click, and to confirm ease of removal, they clicked off effortlessly, then back on and back off and back on.
Every time the click back on felt really snug.
So before I closed it all up, I had to check the old (metal only) quick connect again, and it went on harder, and again huge effort to remove again.
Every time I did clean the pipe on the cooler to be sure no grit or yuk stuff on them.
I have a spare cooler off my D2 V8 wreck, and have recently cleaned the, metal only, quick connect fitting with brake cleaner, and now it clicks on and off nicely .. dare I say like new.
I didn't think to try blow out the quick connect fitting, just that with some grit and oil in them, they probably don't operate properly if care isn't taken when refitting.
But, I think all quick connect fittings will be like this. The fuel return lines.
I've modded the (EU3) external return line with hose and quick fitting at the front of the head. Initially I reused an old fitting I had lying around. Not much space for fingers in there, and impossible to remove it by hand. Had to use the plier tool for them, to remove it, again hard to get it in there. But I got a bunch of new fittings and replaced this one that I've modded. Now a simple press with fingers and it's off.

