Justin,  First of all, you should find "directions" on a label inside
the top lid of the organ. If they're missing or illegible, the text is
found at  http://www.rollerorgans.com/directions.txt

If you wish to buy a reproduction label, see
http://www.rollerorgans.com/store/product_info.php?products_id=420

It's quite easy to change rollers (cobs) on a Roller Organ:  Assuming
the instrument's in correct working condition, crank to play the tune
until its completion.  At that point the cob should automatically reset
(tip toward you and return to your left) ready for the next play.

To change a cob, grab the knob (or loop) on your right, and simply
pull the short shaft away from the cob -- the cob will then be loose
and you can remove it with your left hand.

Installation is just the reverse: With the knob held to your right,
insert a cob (making sure the two holes in the end of the cob align
with the shaft and drive pin on your left), then release the knob to
reinsert the short shaft into the single center hole of the cob (on
your right).  That's it!

Todd Augsburger - Roller Organs
www.rollerorgans.com