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Antique Clocks/Bulova Mantle Clock 330-020


Where is the screw that regulates the clock.
I see the plus and minus stamp marks but am unsure about how to slow the clock.

It sounds like you have a balance wheel type Hermle movement.  The Bulova name doesn't mean much any more as all of the old American companies are gone.  They sold their names to companies in China and they are producing the clocks.  If your clock has a small wheel that spins, it is probably a Hermle.  

Attached to the top of the small wheel that spins should be a small three sided plate that turns independently of the balance wheel.  You will need a small flat screwdriver to move the plate.  As you face the back of the clock look at the + and - .   If you need to speed up the clock rotate the plate toward the +.  If you want to slow the clock, turn it toward the -.  I would not turn it more than about 1/4 turn to start.  Let it run for a day or so and readjust it.

If you have a question with the adjustment, let me know.

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I have been repairing mechanical and electric clocks for over 25 years.

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