and the story continues...

My F4S was examined and the shutter found NOK.
The shop did a repairjob and placed a new shutter under warranty.(no costs)
The machine is back in business which is great.

1. I never would buy any camera without a minimum of warranty, be it 2nd hand or new.
2. Go and spend your $/€/£ in a shop you can trust. It's all worth it when the sh.t hits the fan...