Cant get 4kq differental to lock...

["Jeryd" <Leuck@concentric.net>]

Please help...
    My Differential does not work any more...  I do the switch in my 86 and
all that happens is, nothing....
    It stopped working today.  All I did was install a new stereo system.  I
did have to take off the differential control switch.  I think what might
have happened is the vacuum lost its vacuum...
    What should I do?  Snow season is nearing, and I really want to go visit
my friends up in the mountains.  Should I take the car to the shop?

Thanks for all your help
    Jeryd!
Leuck@concentric.net