P/s belt new, fluid full, will check for foreign objects by the belt in the morning.
How would any of these cause the symptom?
It sounds like a noisy air release valve or something.
It will probably be obvious at this stage that I have no idea about the workings of power steering.
306D 1975 (camper) - rusting away
W116 450 SEL 1975 - sold
W114 long wheelbase ambulance, 3 litre diesel 1974
VW Golf 1 convertable - midlife crisis item
VW T4 van - support vehicle