I haven't run into control problems on these modern Aeolians.  I have
had problems with leaky player actions.  The original motors supplied
were intended to run on 240 volts, but use 120 from the wall.  The
highest possible vacuum is approximately 45 inches.

Eventually there isn't enough vacuum to play all the notes.  I have
changed the motors to the ones that run on 110/120 and have 95 inches
of vacuum available.  I add a dimmer switch to lower the motor speed to
quiet operations and to supply just enough vacuum to have all the notes
play.  The players come back to life.

Howard Goldberg