Ref 6426 crown gasket?

[mechachia]

I just got a 6426, and wanted to replace the gaskets. I believe this is a twinlock crown, so there should be a gasket in the tube and in the crown.

When I took the stem out, there was a tube gasket present, but no gasket inside the crown. Not surprising for an old watch, I thought. I'd gotten a 6mm flat gasket from Esslinger, which I think is the right size, put it in, it looked like it fit, but it would not screw down with the gasket present.

The caseback gasket I also got from Esslinger worked great.

So... Did this watch not have a crown gasket? Did I get the wrong size? Maybe there's a trick to fitting it?

[mechachia]

On further inspection, I think the problem is largely worn case tube threads. I'm not getting thread engagement until I hit the bottom threads, so it's not grabbing with the gasket installed.

So... The current tube is the 24-6000 (no visible splines). As far as I can tell, after I remove this, the 24-6020 is the new style replacement, has the same threads and should screw right in. Anyone know otherwise?

Also, there exists a small metallic case tube sealing gasket (29-06020), but it doesn't seem like it's used with the 24-6020? Most people mention using some Loctite on the threads to ensure water-resistance. Any thoughts on that?

[77T]

Loctite 221 or 222 is often used when installing a tube in the midcase.


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[mechachia]

So the problem - in case anyone is following along - turned out to be that what looked like old, dark metal was actually the old gasket, which had fossilized and cemented itself to the inside of the crown. Once I scraped that out, I was able to install the new gasket properly. Between that and the new case tube, everything is now as it should be.