I too had much trouble installing my first "early A" stack.  I somehow
finagled it in there.  I later purchased the complete set of AMICA
technicalities 1981-1988 and learned how best to install the stack.

The "Technicalities" are available through AMICA, the Automatic
Musical Instrument Collectors Association.  Terry Smythe and John Grant
put their heads together and came up with a great solution.

Here's my "Reader's Digest" version of their method:  Install longer
bolts than original on each end of the stack.  The bolts should be
long enough that when the pneumatics are closed the dowels on the rods
would go through the holes in the guide rail.  The dowels should not go
through the guide rail holes when the pneumatics are open.

Apply suction from a vacuum motor, this will close all pneumatics and
you can put them through their respective guide rail holes.  With the
suction box still running install the shorter bolts and -- Viola! --
painlessly done!

Bill Maguire