Hello Jean-Marc,  _Please_ do not touch the adjustment screw on the
governor!  That screw is not at all for regulating speed.

The _only_ adjustment screw on the Bremond governor (and virtually
all cylinder music box governors) is the screw for the fine adjustment
of the depth of the worm gear against the second wheel, and this screw
_must not_ be adjusted while power is stored in the spring or with
combs installed.  In fact, you cannot adjust it with the governor
installed at all.

This screw should be adjusted only after the governor is completely
removed and with the governor held in the hand as you press upwards
on the first wheel (gear which is driven by the great-wheel or large
cylinder gear).  If you attempt _any_ adjustment whatsoever of the
lower bearing screw, it is highly likely you will cause a "run" and
cause very serious and expensive damage to the cylinder, necessitating
a complete repinning job, and many broken comb teeth will be broken and
comb tips and dampers will be wrecked.  In a word: DON'T!

Once the proper gear mesh is adjusted with the lower bearing screw,
it should never be touched again unless gears need to be replaced.

If the governor does not run at the proper speed, it may be due to
dirt and old dried-up lubricants, or wear in the worm and second wheel.
If these are in good condition, the proper method of adjusting playing
speed is by adjusting the blades of the air-brake (fan) either inward or
outward slightly, to increase speed or to slow down the speed.  This
adjustment should _only_ be done with comb(s) removed, and spring power
let down.

If you have already tampered with that screw (or _any_ screw on the
governor) you should halt right there and do no more.  In all cases,
the first step should be unscrew and remove the comb or combs from the
bedplate before ANY attempt at adjusting is done.  After removing the
comb(s), next you need to let down ALL the mainspring(s) power, until
you can rock the spring barrels back and forwards a tiny bit with no
spring-back.

This is a tricky procedure and would be difficult to properly explain
in an email.  But it _must_ be done, before you can safely unscrew the
single screw which attaches the governor body to the bedplate.  Some
governors by Bremond are mounted with a screw from underneath the
bedplate, and later ones are mounted with a screw from above.  But do
_not_ try to unscrew or remove the governor until the combs are removed
and all power from the spring(s) is let down to zero.

Even after safely removing the governor, the proper adjustment is often
quite tricky and not a simple procedure, particularly when the gears
have wear.  This is why it is truly best to leave such adjustments to
a music box expert.  Not a clock repairman -- nor a jeweler, nor a
tinkerer nor amateur -- but only an experienced music box specialist.
In Switzerland, I would recommend Michel Bourgoz in L'Auberson.  You
cannot find a more expert music box person anywhere in the world today.

If you have questions I have not adequately answered, please be welcome
to email me directly and I will gladly try my best to help you.

Reg Smith - Sublime Harmonie Antique Music Box Restorations
Dahlonega, Georgia, USA
musicboxrestoration@gmail.com.geentroep [delete ".geentroep" to reply]