More Pentosin Leak

[spsherm@ibm.net]

Thanks to Doyt and Orin (and others) for the suggestions...

As they suggested I cleaned things up, refilled, and took a short drive.
Again the brake lite came on, and when I popped the hood, penosin was
foaming out of the reservoir at the hole in the top...  Unfortunately
the trip was a bit too long and so much oil came out that it was unclear
if the foaming out the top was the only cause...

So my question to those that might know... Short of buying a special
pressure gauge is it "safe" to assume that the foaming oil is caused by
a bad pump and replace the pump?  Or is there another likely cause, and
if so what and how can I diagnose what it is?  [BTW another symptom I
noticed was rather hard steering;  could be low pressure from a dying
pump, or a leak somewhere I guess]

Right now, with the penosin a bit below the low level, at idle in the
garage, the penosin will foam up again and "boil" out the top.  This is
with no motion on the steering rack, and noone hitting the brakes.  

Suggestions and or interpretations welcomed.

Thanks in advance.