Tightening screws that attach the piano's legs may not always
stabilize the legs to solve a shimmy problem.  In most Ampico pianos,
the threaded machine screws that attach each leg to the piano are
screwed into cast iron plates that are recessed into the piano body.
These plates, in turn, are held in place by wood screws that can
become loose over time.

If this situation exists, the only way to stabilize the legs to remove
each respective leg and tighten the wood screws that secure each of
these cast iron plates.  The pedal lyre is also often attached in a
similar manner.

Dave Saul
El Cajon, California