I just bough a 2006 287b and new grapple. The grapple will open but will not close. There is no response from the thumb switch when I push it forward. No noise from the pump. Nothing. Lifted cab and tried to trace wires. Everything seemed in order. Was difficult to follow wires once they go through connectors Disassembled right handle and still no visual problems. Opened up actual switch and found corrosion. Cleaned and put back together. Now I have no response pushing forward or back. Grapple will not open or close. All other controls work fine. Desperate to get it working I cut and stripped the four wires leading to the switch. Touched them in every variation possible. Nothing. Checked fuses in panel three times. Nothing is blown. Any thoughts? Where do the wires eventually lead? What can I trouble shoot if new switch does not work. I have no wiring diagram or user manual. Can't find anything online. I would appreciate any help.