Hi All,  Perhaps we should clarify some facts about the incense sticks.
We use mild scented (cinnamon, apple, etc.) and non scented (when we can
get them) which we purchase at craft shows.  The potent ones are out --
allergy problems!

The incense test is just one of several tests we use when checking the
tightness of a stack, both before rebuild and after rebuild.  With the
aid of an auxiliary variable speed vacuum pump, we use the incense sticks
to get those insidious little leaks that haunt a rebuilder.  Because of
the noise of the vacuum unit tends to enter the stack, the use of a sound
sensing device may not be dependable.

A stethoscope also will not pick up the sound of air passing through
porous leather valve facings and gasketing.  We have never seen any
deposits of smoke residue after this type of testing.  We have seen many
pianos where the case and components were coated with tobacco tars and or
coal tar (in English pianos <g> ), and still not any significant damage
due to smoke.

If, on occasion, we need to use this test at a customers house, we always
ask permission and explain the reason for its use.  Usually the customer
stands there transfixed while we do our checking.  It has been a great
diagnostic tool which helps to sell rebuild jobs, and improves customer
confidence in our knowledge of how player mechanisms operate and where to
look for problems.

Happy Testing!

Bob and Sonja Lemon¶
Lemon's Player Piano Service¶
Sacramento, CA