Certina Club 2000 25-66M

Service: Certina Club 2000 With 25-66M Movement

This is a wonderful vintage Certina Club 2000.

Although it’s one of the lower grade Certinas, it’s still beautifully finished and it has a solid stainless steel case.

All the Certina in-house movements that I’ve encountered are great performers and you can accurately regulate them with the micro-regulator.

Sadly, the 25-66M movement in this Certina wasn’t running.

Certina produced the 25-66M from ’75 till ’77. This Certina has a serial number that consists of 9 digits and that indicates that it’s a ’74+ piece so it’s all adding up.

There were some problems with winding because you could wind it forever without it ever building up any resistance. If you think that sounds like a broken mainspring, you’re right!

It also had some problems with water resistance because at one time the crystal fogged up during an exceptionally hot day.


Before you start working on a mechanical movement, make sure to remove all the power from the mainspring. This way, you’ll minimize the risk of damage when working on the wheel train later.

Move the click away from the ratchet wheel and let the crown slip between your thumb and index finger.

Lift the balance and the pallets.

Certina club 2000 25-66M
Balance and pallets removed

Turn the movement around and lift the cannon pinion. The cannon pinion is installed on the center wheel post so you won’t be able to lift the center wheel later if you don’t remove it.

As you can see, this movement is a bit different.

The crown wheel is located within the wheel-train bridge instead of the barrel bridge. The ratchet wheel overlaps the wheel-train bridge as well so you’ll need to lift the crown wheel and the ratchet wheel before you move on.

Lift the wheel-train bridge to expose the wheel train.

Certina Club 2000 25-66M
The crown wheel, ratchet wheel, and wheel-train bridge removed

Remove the escape wheel, 4th wheel, and the sweep second wheel.

Take out the barrel bridge and lift the main barrel.

As suspected the mainspring was broken, so I had to find a new one. This was a bit of a challenge because the exact dimensions that Bestfit and the GR folder mentioned, were obsolete at the warehouses.

Luckily, a friend had one in his stash of parts so he sent it to me.

Certina Club 2000 25-66M
Broken mainspring

Lift the center wheel cock and remove the center wheel.

Certina Club 2000 25-66M
The barrel bridge, main barrel, wheel train, and the center wheel cock removed. The top plate is completely empty

Flip the movement around and begin with the bottom plate.

Certina Club 2000 25-66M
The bottom plate is completely empty

Pre-clean the pivot holes and bearing jewels with a peg wood.

Clean all the parts in the watch cleaning machine.


Start with the center wheel, the center wheel cock, and the main barrel.

Lubricate the post of the center wheel before you assemble it and lubricate the arbor on both sides of the main barrel as well (both with Moebius HP1300/D5).

Certina Club 2000 25-66M
The center wheel, center wheel cock, and the main barrel installed

Reinstall the barrel bridge.

Certina Club 2000 25-66M
The barrel bridge reinstalled

Place the escape wheel, 3rd wheel and the sweep second wheel and refit the wheel-train bridge.

Install the ratchet wheel and the crown wheel.

Don’t forget to lubricate the crown wheel shim with a tiny bit of Moebius HP 1300/D5.

Certina Club 2000 25-66M
The wheel-train bridge, ratchet wheel, and crown wheel installed

Turn the movement around and start with the motion works and the keyless works.

Lubricate the posts for the setting wheel, the return bar, and the cannon pinion with Moebius 9501.

Don’t forget to lubricate the finger of the set lever spring that is in contact with the set lever.

Certina Club 2000 25-66M

Flip the movement to the top plate and start with the pallets.

Lubricate the exit stone of the pallets with Moebius 9415.

Replace the balance and enjoy watching the movement come alive.

Take out the Incabloc jewel holes and jewels on both sides and clean and lubricate them (Moebius 9010).

Certina Club 2000 25-66M
The 25-66M fully reassembled

After I cased the movement, I fitted a new crystal (with a tension ring).

I also fitted a new case back gasket which I lubricated with a lubricating sealing grease to increase/restore the water resistance.

Finally, I treated the inside of the crown with KT-22 grease. It makes the crown wind smoothly but more importantly, it protects against moisture and rust and creates a waterproof seal.

During test running the mainspring broke again! I guess it must have gotten bad somehow during storage.

I had to order a new one but the exact dimensions still weren’t available.

In the end, I ordered a mainspring that was 0.005 mm thinner – 0.115 instead of 0.12.

0.005 is mm is only slightly different and the newer mainsprings are a bit stronger than the older ones so that shouldn’t be a problem.

The amplitude of 328 degrees is proof of that.

Certina Club 2000 25-66M
The Certina Club 2000 after the service and functioning 100% again. Blue dial with some discoloration. Some would call it “tropical”.

What do you think of this Certina? Do you have a similar watch? Let me know in the comments below.

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4 thoughts on “Service: Certina Club 2000 With 25-66M Movement”

  1. Hello Melvin,
    I’m servicing a Certina Bristol 235 with cal 25-66. Of course it has a broken mainspring.
    Could you please share the source of the slightly different mainspring? Thanks.

    1. Hi, I’m afraid there aren’t many dial cleaning techniques and they’re all very risky. All I ever use is the hand dust blower and a piece of Rodico. My best advice would be to leave the dial alone as much you can.

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