Service: Longines Advocate 9LT (25.17ABC)

 In Watchmaking

This is a beautiful Longines Advocate watch. It’s in excellent condition apart from a scratch on the dial. It looks like somebody slipped while trying to lift the hands. It’s a real shame, but it happens, though I wouldn’t want it to happen with any of my watches. Or even worse, on a watch I’m working on that isn’t mine.

The serial number dates this watch to 1953. If you’d like to date your own Longines, you can try this Longines Year Identifier.

The movement is the Longines 9LT. It’s a movement with an indirect subsecond. I’ll come back to what that means later. This particular one is a 25.17ABC with a monometallic balance. There’s not much to find about this movement, except for the standard info.

This Longines Art Deco needed a service. The power reserve was way down from what it used to be, and it sometimes suddenly stopped.

Disassembly

Make sure to remove any power from the mainspring and lift the balance and the pallets.

Be careful because the pallet cock in these particular movements doesn’t have 1 but 2 jewel holes.

Remove the hour wheel and the cannon pinion on the other side of the movement.

Longines Advocate 9LT
Balance and pallets removed.

As I said before, this movement has an indirect subsecond. In this case, that means that the 4th wheel isn’t the seconds wheel.

Instead, this movement has a pinion with a long pivot to attach the subsecond hand.

The 3rd wheel drives this pinion, and the pallet cock covers it. That’s why it has two jewel holes instead of 1.

Longines Advocate 9LT
The subsecond pinion engaged with the 3rd wheel.

Lift the train wheel bridge and then remove the wheels (escape wheel, 4th wheel, 3rd wheel, and seconds pinion.

The barrel bridge covers the center wheel.

Longines advocate 9LT
The train wheel bridge and the wheels removed.

Usually, you’d remove the ratchet wheel and the crown wheel. However, in this movement, the crown wheel is secured by three small screws from below. The click-spring is on the back of the barrel bridge as well.

Remove the ratchet wheel and then lift the barrel bridge.

Longines Advocate 9LT
The backside of the barrel bridge. You can see the click-spring and the three screws to secure the crown wheel

Lift the center wheel and remove the main barrel.

Longines Advocate 9LT
Top plate empty.

Flip the movement to the other side. Start with removing the set lever spring.

Then remove the rest of the motion work and the keyless works.

Longines Advocate 9LT
The bottom plate of the movement empty. The red arrow points to the spring that keeps the second’s pinion under tension. Remember to check if the spring is on the same side when you reinstall the pinion.

Clean all the parts in the watch cleaning machine. I use L&R #566 cleaner and L&R #3 rinsing solution.

While the parts were being cleaned, I polished the crystal. You can read this article if you like to know how to polish a watch crystal.

Assembly

Start with placing back the wheel train and the main barrel. Remember that the barrel bridge covers the center wheel, but it needs to be under the wheel train bridge as well.

Lubricate the bearing jewels of the wheel train bridge with Moebius 9010 or similar.

Longines Advocate 9LT
The main barrel, wheel train, and the wheel train bridge replaced.

Remember to fit the crown wheel first (from the back) and reinstall the barrel bridge. Fit the ratchet wheel.

Lubricate the center wheel with Moebius HP1300 or similar.

Longines Advocate 9LT
Barrel bridge, ratchet wheel, and crown wheel reinstalled.

Turn the movement around and install the motion works and the keyless works.

Lubricate the shaft of the center wheel with Moebius 9501 or similar before you fit the cannon pinion. Use the same grease for the keyless works as well.

Lubricate the bearing jewels (except for the one for the pallets) with Moebius 9010 or similar.

Longines Advocate 9LT
The bottom plate finished.

Turn the movement around and reinstall the second’s pinion (remember to check if the spring is on the right side).

Reinstall the pallets. Be careful because the pallet cock covers both the pallets and the second’s pinion. Keep testing while you gently push down the pallet cock a little at a time. Lubricate the pallet’s exit stone with Moebius 9415.

Reinstall the balance and enjoy watching the movement come back alive.

Longines Advocate 9LT
The Longines 9LT ticking happily.

I like to keep the movement running like this to see if it runs steadily and to test what the power reserve is.

The 9LT kept running for 45 hours, so that’s not bad at all.

I fitted the hour wheel and a washer (that was missing) and re-cased the movement with the dial and hands.

Longines Advocate 9LT
The Longines Advocate after the service. I also polished the crystal and fitted a new burgundy strap.

Do you have a Longines Advocate or a similar Longines Art Deco Watch? Let me know in the comments below.

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Showing 6 comments
  • Avatar
    lisa
    Reply

    I have an Art Deco Longines Advocate watch, model 8789173. I emailed some more pictures to you and was wondering if you could give me any information you may have.

  • Avatar
    Christopher Lord
    Reply

    Hello Yes I have just bought a beautiful 1954 Art Deco watch with this movement, serial 9272415. I have just taken the back off because it is not running. It seems to be very clean and I have bought it because I had a similar Longines but without the second hand which my daughter loved so much that I gave it to her. So if I can get this working we can have father and daughter watches in this same rectangular style. The crown won’t turn so I suppose it is fully wound. Pulling it out to change the setting of the hands works fine. My first one wasn’t working and I actually blew gently on it and it started going which was a magic moment. But that hasn’t worked this time. I am tempted to take it apart but I suppose I should get it cleaned. I don’t know how easy it would be to find a replacement movement.

    • Melvin Hollenberg
      Melvin Hollenberg
      Reply

      Well, I have 24 Longines movements, but unfortunately not a 9LT. There aren’t any affordable ones on eBay either. At the moment, at least. I’d advice to have it serviced/overhauled by a professional watchmaker.

      • Avatar
        Christopher Lord
        Reply

        Yes Melvin I’ve come to the same conclusion. I’ve never had a watch serviced before but on balance I’m happy to support someone who is still doing this kind of work.

  • Avatar
    Richard Becke
    Reply

    Well done 🙂 I have a similar 1953 Longines – movement serial no. 9245676, case serial no. 0196815 – which is not working. Maybe you could help me identify the model if I send you some photos?

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