86 4kq fornt diff won't lock

[Frank Sanford <fsanford@frontiernet.net>]

The front differential on my 4kq will not lock. When you turn the diff
lock knob to the "1" position, nothing happens - no led light up, no
noises - nothing. in the "2" position, the rear does lock-up fine
however(verified with car up in the air). What are some of the things to
check? I've never messed with a quattro transaxle and I don't have a
bentley (I know I need to get one, but I've had more pressing needs for
my $ lately) so I'm not sure where to start. Any suggestions would be
appreciated.

Frank
'71 914
'86 4000CS quattro