5 year thread but still relevant. For my grapple, I just switched from pioneers to flat face, thinking I've had enough dealing with "just a thimble" full each QA swap. But the very first time I tried reconnecting it, the line pressure made it impossible. I read through this thread and couldn't believe I traded "just a thimble" for a pressure relief assembly.
Happy ending, I raised the loader arms so the lines could gravity drain back to the reservoir, then turned the tractor off but left the key in, and oh my it worked. Coupled back in with little effort.