Smitty, when you say that you're taking off the grapple, do you mean that you are just taking the grapple off the FEL or taking the whole FEL off? The reason that I ask is because when I got my GL4740, the first 2 times I took the grapple off I had sheer hell connecting it back up again. Now, I'm used to taking the whole FEL off the B2400 and the M5700 at the farm so I'm familiar with shutting off the engine and relieving the pressure in the lines by wiggling the joystick. That's a mistake you only make once. It was only during my second hand-to-hand combat session with the grapple that I realized that the two lines I was having trouble with weren't controlled through the FEL joystick. The grapple open and close functions were controlled by a separate lever on the right fender. Once I had relieved the pressure on that line they connected back up easily.
Now, I don't mean to imply that you are as big an idiot as I was, but does your grapple have a separate control lever too? Once the pressure is off the lines they should connect back up without a problem.
If you figure it out, let us know because it might be a problem that I have waiting to be "discovered" and it sure would save me a lot of time and frustration, not to mention busted knuckles, if you solve it for me first.