two 4000q questions

[Nimmer, George]

I have a 1985 4000S quattro.  There are two problems I'm looking for
advice on.

1. when the engine is cold (e.g. first thing in the morning) i go to
start it, and it starts up immediately.  when the engine is warm (e.g.
I'm running errands, and making many short trips), it takes two or three
tries to get it running.

2. the rear diff does not lock.  I've tried putting the switch to
position "2" and driving slowly, quickly, in reverse, going straight,
turning, etc... and it will not lock.   The center diff lock works
great.

Thanks all!!
please respond to me in email
George