Guess what - I did a whole bunch of experiments and it turns out that the
upper spray arm is turning well and throwing enough water. I tied a string
at the base and left about 2 feet hanging to the side (weaving thru the
upper rack) to see if the arm revolves enough - the 2 ft string was rolled
up completely when I opened the washer after about 15 seconds. So RPM seems
fine.
I taped up the lower arm and closed off the third one at the top and there
was water all over.

Then I removed the tapes etc. and did the glass test and glasses filled up
in no time.

Now I am really at a loss...

AJ