jdm

I don't think that this watch has ever had a different mov.t than the current one. It is a Japan watch as indicated on the back, visible in the first picture, so no chance of using a Swiss mov.t. YSL is a fashion brand like another, they are not tied to any country or manufacturer.

Personally I would polish the crystal accurately, and use generic gaskets.

Strong and quality for sure, but the tips folds easily when pressing hard, and is not even close to the shape needed to open case backs. I really recommend to avoid to work on watches using a Leatherman tool. The watch is made adequately for its cost and purpose. Damage depends on the person which has assaulted it and nothing else. To hold it steady you can cut two pieces of wood to go in between and around the lugs, and place in a vice. It is difficult to pry open a square back without leaving any marks, all depends by the blade and technique used. For example, you NEVER twist the tip, but simply go around until it pops.

In mass produced Japanese watches, mov.t ALWAYS comes out from the back. No need to overthink when things are immediately evident like in this case.

No tricks here. Just be aware that if the back is real tight, you'll need a press to close it.

Nothing like that here. Cheap pressed in back type.

No need for expensive tools. Work around it with an x-act type knife first. Watch your hands, wear gloves, etc. Then when you have got a leverage, use the other tools.

Welcome to the forum. I don't think there is any estimator course or school, everything is based on your reputation and knowledge of the market.

I can't answer your questions but I know that most people here like to introduce themselves first.https://www.watchrepairtalk.com/forum/23-introduce-yourself-here/ And that pictures are needed in technical threads.

It's common for watch owners to join the forum just to get help with a current issue, and then never update. Anyway, his city is mentioned in the first post.

Yes, leaving the bracelet is perfectly fine. All you need is to position it to be able to look at the back and crown to spot the bubbles, if any. Also, testing above 5 or 6 bar , which is a lot already, is next to useless.

So, how come the crystal came out with the retainer still in place? Brute force broke something?

Welcome to the forum. My opinion on your problem and similar ones is that if something is stuck by mechanical force, by the same shall be removed, but if it's hold in place by glue or cement, use a solvent before forcing.

What about a needle or pin. Is this you 1st crystal replacement? Also, you may take the time to introduce yourself in the dedicated section of this forum.

Cousin UK has it, or you can contact SII in Hong Kong. However if you really want to preserve the watch I suggest that you find someone to repair it, in Singapore or other places. It is not said that any part is needed. Also, replacing the mov.t may not be that easy either if done the right way, as some threading may be needed to avoid an hack job.