Another way around the possible QC valve failure is to just remove the check balls from them. You must however remove all the balls from any QC that might possibly be mated with one that has had the ball/valve removed. IF one side still has a ball, that one ball will not open and will block the flow.
In the case of the loader, that is 2 male and 2 female connectors, or 4 check valves and springs. Since it is common practice when disconnecting a device to reconnect the pair on the device, or the pair on the tractor to themselves to maintain flow and keep the connector clean, only a little oil is leaked/lost during the change. This has the added benefit that in the event a connection is accidently released while the engine is running, the pump dosn't get deadheaded and damaged, but the oil is allowed to leak away and not build any pressure... Keeps the functionality of the QC, but removes the risk...
If you unscrew the QC from the hose end and look in the threaded hole you will find a circlip/snapring, a spring retaining plate, spring and the checkvalve ball. Takes just a few minutes with some snapring pliars, to remove them and re-install the QC back on the hose.