"Dave, I can't do that" fired this volley in
:

Having moved the cutoff down to 35,
it now cuts in at 15. The other adjustment screw is to increase the
cut off pressure and increase the range upwards so you can have 30-cut
in and 60 cutoff for a differential of 30-lbs. I need the opposite of
that and move the cut-in higher for a differential of 10-lbs.

You're (I think) missing the point. You can control both the range and
the cutoff pressures with those two screws. It takes a knack, and some
experimentation, but you can.

My house has lousy "flow control" elements in all the fixtures. Some are
simply not removable without destroying the fixture. I've had to do the
same thing you need to. In my case, it was raising the top-end pressure,
but also shrinking the range. But I can "go either way" on the Pumptrol
units. Play with it awhile, and you'll figure it out. It's not
intuitive.

LLoyd