My power steering has been squealing on left turns for about a week and
has slow return to center after executing left turns.  Reservoir reads
as FULL when checked, cold or hot.  The reservoir exterior is stained
with fluid and some embedded crystals.  No drips on the driveway so the
problem is either minor (hah!) or new enough that the leak hasn't made
it to ground yet.

I cannot pinpoint the source of the leak to any of the hose fittings or
to the filler opening so my money is on the pump - and that'll be a
warranty item for the dealer to deal with.

Full reservoir plus leak seems to indicate overfilled PS system, which I
find unlikely; the best indy Volvo shop in town did the last recommended
maintenance and I'm sure they know better than to add fluid when none is
needed.  Squealing on turns plus slow returns suggests the pump is at fault.

Does this seem likelier to be a PS pump problem, or a hose problem?
Short of the pump going out altogether what's the worst-case event if I
keep driving it until the dealer has time for it more than a week hence
(I'm still under warranty)?

(Yes, I need to buy the service manual!)