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IWC ref. 3401 hummer with stubborn caseback

  1. w154 Apr 5, 2019

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    I’ve picked up my first hummer !

    It’s an IWC ref. 3401 which looks in pretty good condition on the outside, but I’m struggling to get the back open (the only thing opened so far is a gash on my finger). There’s a very clear undercut around the entire perimeter of the CB, but putting my case knife in isn’t getting me anywhere. Perhaps the problem is that the groove is quite high (high enough to get a fingernail under), and the case knife is probably just hitting the midcase itself. Any suggestions on how to crack it open ?

    You can see the undercut pretty clearly.

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  2. w154 Apr 5, 2019

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    Success thanks to a tip from @JimInOz... it was all about the profile of the blade and a crappy free-gift knife did the job. Key was a chisel like blade, so flat on one side and a reasonably steep slope on the other. Really happy to find it’s a signed movement rather than a replacement, and that on first inspection there’s no battery leakage. I’ll order a battery and hopefully it’s good to go !

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  3. Canuck Apr 5, 2019

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    Had it not occurred to you that perhaps, just perhaps, you should give up trying to remove the back? If using a case knife isn’t a skill you have learned, you can do a LOT of damage when the case back suddenly pops off, and you skid across the movement with the tool.

    While I typed the above reply, apparently you got the back off. Do you have a case press at the ready for when you try to put the back on?
     
  4. w154 Apr 5, 2019

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    It did occur so I took an hour or two away from it and gave it some thought. The key was the tool and I found something suitable and then it came off first time. I suppose the same will be true for putting it back on. If sitting on it, wedging it in the gap of my front door, hitting it with a hammer, or driving over it doesn’t work, then I’ll have a look in my drawer and see if I have a case press.
     
    Archer and dennisthemenace like this.
  5. w154 Apr 5, 2019

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    So now the next problem, which I’m sure is going to require a real watchmaker :D

    I bought a 344 silver oxide battery and popped it in, and it started humming away nicely and with the second hand running fine. So I thought, let’s set the time and the date. So I changed it to the right time, which was fine, then started to change the date which worked for a few days but then stopped on the 3rd. Now turning the crown at the first stop does nothing, and no humming anymore or second hand motion.

    Edit. It’s gone to the 5th now but it’s not really driving the date wheel well, and it’s still not showing any signs of life.