Where is the forward solenoid located on a Caterpillar 966K with no forward movement?

[Spencer Cawoddy]

I'm trying to troubleshoot a no-forward issue on my Caterpillar 966K. The machine has reverse, but it will not move forward at all. Right now, I'm thinking the forward solenoid may have failed, but I'm not exactly sure where it's located on this machine. Before I start tearing into things, I'm hoping someone can point me in the right direction. Is there an easy way to test the solenoid before replacing it?