Remove the lid and carefully remove the rubber gasket with a metal tweezers

Be careful not to break it

If it is already broken there is no need to panic, replacement can be bought for cheap price, you just need to measure the correct diameter and search for “XX mm watch gasket)

(Optional) I used a regular toothpick and rubbing alcohol to clean the remaining gunk under the lid. You can use blower to remove debris from the watch movement. Plastic spudgers can also be used for the coarse cleaning

Next, bend two small clips upwards. They are fragile so be careful

Finally, remove the white plastic movement holder.

When removing it the whole movement might want to get out. One of the tricks to avoid that is gently keeping it pressed down through the hole in the middle while pulling the plastic upwards with tweezers.