Dust sucking into the system is the least of your problems.  Those
valve blocks are all cracking at the seams, the inside valve seats
are loose and leaking, the valves are powder, the pneumatics are all
crispy.  Sounds like you are wasting your time just trying to fix it.

If the elbows and tubing are in that bad of a condition then the
bellows cloth and felt and leather valves will also be beyond hope.
Find someone to restore the whole player system or do it yourself.
I would suggest you not do it yourself until you have restored several
88-note players and are happy with them.  Even if someone restored it
twenty years ago, the cloth is not airtight today because our sources
of cloth sent us faulty cloth.

D.L. Bullock    St. Louis
http://www.thepianoworld.com/