"Andrew May" wrote in message
...
On 08/02/2012 15:30, William Sommerwerck wrote:

You can't ignore the screeching noise. It's screeching for a reason.
I'd start by trying to track down the cause.

What I am at a loss to explain at the moment is why it can move
through that position when starting up but not after focussing.

That might be an important clue. But find out why it's squealing.