Joyce Brite asks about changing piano casters for modern wheels.
We have done this several times to make them easier to move about the
museum.  We use a 'stringing bench' -- the term used in UK, anyway.

It's basically a fold-up steel framework with curved skids and two
wheels.  You erect the contraption, hook its steel projections under
the back of the piano and then simply roll the whole thing over
backwards.  At a pinch, one person can do it, but it's probably easier
with two.

The bench is really intended to support an upright piano on its back
whilst re-stringing it, hence the name.  You can move the piano about
on the wheels under the bench if you need to.

Regards,
David Evans - Revelstoke Nickelodeon Museum
Revelstoke, British Columbia, Canada
http://www.revelstokenickelodeon.com/