Paul,  I have been having problems with the diff lock and the indicator
light switch.  It seems important to know a few things, first the indicator
light is activated by the lock itself - not the switch.  The switch
requests the lock to be engaged but the actual engaging happens when it is
able too - this engaging causes the indicator light to come on.

I do not know what you mean when you say "pulling the switch in"?  Mine was
back to front because the vacuum lines had been swapped around!

I think you should not drive on a hard surface with the lock engaged.

Hope this is some help.
Don