This problem is real enough and not solved by changing tubes, because
the stack split is thanks to the placing of the divider and if you try
shifting tubes you just end up with a spare one at one end and no tube
for the tracker-bar at the other.  Plus the piano will transpose up or
down a semi-tone !

English upright Duo-Arts (only made after 1919, I believe - before that
DAs were imported) all have the low divide like Robbie's 88n, between
Eb and E natural, the 88ns all have it between E & F.  Examination of
very early 1914 DA rolls here shows that they divided E/F but quickly
changed.  Gordon Iles who worked for (UK) Universal Music before WW2 had
a story that there was no intention to have a different divide than E/F
(44/44 notes) but the first batch of Weber Duo-Art grands to go out had
a mistake in the drawings which resulted in the stack divide being
incorrect.  This was not discovered for quite some while, by which time
it would have been too expensive to recall the pianos.  So the rolls
were changed instead.  In his own rolls, both 88n and DA, E natural was
always themed both sides at once so it would play correctly with either
divide.

(By the way, someone here said the other day that no-one uses notes 1-4
 and 85-88 any more.  Not so - see the John Farrell HPC new issues !
 He's always with Fats Waller tinkling away at the top.)

Dan Wilson