His cage is now in the living room, and twice a day I put him with the others in the bird room. When I hear him screeching I go and take him back to where his cage is.
He has developed an insane love for Paul and the highlight of the day is when he can sit on his jeans and pull out the fabric while he listen to him whistling, or just talking to him.
More or less the screeching is gone.

So pleased he has settled Barbara...
what do you think was wrong?
Zippi paces and yells like that on times, I recon he is annoyed with something...but... I don't know what.. as you say its not all the time, just now and again...
I put a towel over the top of the cage, sides still open... this seems to settle him... after a while I remove towel and he is ok...
They have there ways just like us!

I really have no idea, Jan, they have such complex minds! Tielfan made me think when she observed that such a behaviour is of a bird who wants to go somewhere and doesn't know its way to that place.
I thought he was just unhappy in a general way.
Turns out that actually he did want to move from there and now it's quire easy to help him.

You could try and do the same thing, when Zippi does that just move him somewhere else, maybe a perch next the window or on your lap.
How tame is he?