I have the same problem with some snap off backs without notch, you can't get under them whatever you use (also the best case knifes). I bought one of these (similar model, same system). Works great:

However, if you have just this one watch with that problem, you could go to a watchmaker every 2 to 3 years where you also get the battery, as you won't get an amortization of this tool. But many collectors want to be 'independent' and like to do this kind of work themselves, and then it's a different thing.

On thing you also have to keep in mind: On some watches, you won't be able to get the case back on, as your fingers cannot apply enough pressure. You need a case pressing tool for that (with a lot of dies which might or not fit the size of your watch), which means $$,$$ again.

And again: A watchmaker would also have the gasket at hand, in case it has to be replaced.

 

I have a multi die press system that I ordered pretty cheap on AliExpress. Well worth it for putting any snap on watch back. Also useful for
removing watch crystals and replacing them with new ones.

 

thanks for the answer,great idea,i will buy the tool as i want to be in control myself,there
should be no problem with getting it back on as all seikos snap on with a clear "pop" sound,just by using fingers ,several videos on youtube shows that

 

Just because a case "pop" doesn't meant it's properly seated. Some cases you can push back with your fingers; some you can't.

 

There is another way of getting these case backs off, by using the yellow thing shown in the image instead of a regular case opening knife. You have a much better and stronger leverage, also from the ideal 180 degrees positon rather than 90 degrees (sideways). But with a more expensive and rather new Seiko Dolce (dolce = Italian for 'sweet') you might want to be on the safe side. If you do not want to keep the watch in your hand whilst doing this, you need a big and stable holder to keep the watch secure in it's place.

 

I found razor blades to work quite well, tapping one into each side, opposite one another. If that doesn't pop the back off by itself, it at least lifts the back a little so that you can get under it with a more substantial knife, on the sides that are still accessible.

 

. . . . and even under a loupe i dont see any notch, how is it possibe to open it, best if possible without scrathes, off course, . . . .

Many cases don't have this feature.

Opening one without creating damage is largely a function of skill.

I found razor blades to work quite well, tapping one into each side, opposite one another. If that doesn't pop the back off by itself, it at least lifts the back a little so that you can get under it with a more substantial knife, on the sides that are still accessible.

When thinner conventional instruments fail the single edge razor blade is an interesting tool.

Too much caution can't be exercised when utilizing them in this role.

 

Too much caution can't be exercised when utilizing them in this role.

Yes, good point, I am glad you mentioned it!

 

Swiss army knife.

 

Or a No.11 exacto blade. Push it straight in between the case and the back, twist a little and walla!