M934 leaking front wheel lock in switch

[Bill Nutting]

I just brought home a 1981 M934. The only issue we know of is there is gear lube leaking out of the "front wheel lock in switch". this is the switch on the dash that engages/disengages the front wheel drive. After driving it home 1000 miles we collected about 2 quarts of gear lube. I'm pretty sure it is coming from the transfer case. Has anyone heard of this? Is there a TM that shows the air circuits on this truck so I can see if a line is connected wrong?
Thanks...