I don't know if you got the problem sorted out or not but I ran into similar trouble with our 2007 257B2 (4,600hrs) this past month. I'm over in Nova Scotia, Canada. I use the aux hyd for running a grapple attachment just about on a daily basis. Engaging the thumb button on the right joystick should perform the function of the grapple (grab and release). The other grapple function is to rotate either way 360º, and that is done by pressing down on one of the buttons (top right) on the left joystick, in conjuction with the thumb button on the right joystick.
It's only today after getting their mobile tech service to the yard. His determination is that the ECM (part # 2160658) under the floor board is not working correctly. He said, "There is no output from pin 40 and pin 42 which is for A1 solenoid and no ouput for pin 58 and pin 42 which is A2 solenoid. This is directly from the ECM. The inputs are working as they can read using the laptop but nothing comes out of the ECM as 12 volts on pin 1 and 3."
Choices are to buy new from CAT (about CAD$10K), or a reman (about CAD$7K). Expensive either way. Or, find someone to rebuild it.
I went looking online and far east sellers have them at USD$1400 to $2900. Then I found a company in Texas that rebuilds them by sending in the core to fix, or as a part refund if buying a rebuilt one they offer for USD$2495. Goecm.com, anyone have experience with them?