Old Washbasin Faucet Not Turning Off Properly - Possible Gasket Replacement or Full Battery Change?

Hello. My washbasin faucet is about 12 years old and over time I have to turn the tap on more and more. I thought that I would have to disassemble it and replace the gasket and it would be OK. I removed the knob itself and I would have to remove the casing, but it wouldn't work. I've tried various ways, but it won't budge. I think that in these models it may not be necessary to disassemble it, but replace the entire battery. I don't want to spoil it, because for now it can still be used. Maybe someone knows what to do with it?

Turn off the water so that your house doesn't flood and then replace the entire head. It doesn't cost much and it will probably help.

It will definitely be removable (they must have put a head there), or it will be a push-in or screw-in cover, but after 12 years it may have become rusty or may have become a bit tarnished and I'm not surprised that it's hard to move.

I don't want to replace the entire battery at once, maybe I can just replace the seal, unless it can't be disassembled :{

It is demountable. Forcefully push the cover off, e.g. with a sharp screwdriver. The rest is threaded and replaceable. You will need rubber gaskets. You can make some money, for example, from a piece of rubber from jars or an inner tube. Insert a short screwdriver under the cap (cover) and tap it with a hammer until the cap comes off. Then use a 17 or 19 wrench and unscrew the whole thing. After unscrewing it, there will be a gasket or its remnants underneath - please turn off the water supply to the tap first.

Wrap this head cover tightly with a strip of rubber from a bicycle inner tube so as not to damage it, squeeze it with a notch wrench and unscrew it.

I took it apart and put it back together, but......There's just a small dilemma As a colleague of box.mann wrote, "Forcibly push off this cover, e.g. with a sharp screwdriver." As for this cover, I knocked it because it didn't want to move, I sprayed it with rust remover and the same thing happened, until I finally took it with my fingertips and squeezed it and it unscrewed normally, but because of the knocking with the hammer, the whole fastening broke apart, the plate on the bottom was even a piece flew away. I quickly unscrewed the hoses, unscrewed it from the siphon and took it off together with the sink, because earlier I couldn't unscrew the head itself. I unscrewed the head in a vice and put on a new rubber band, but the battery mounting nut is completely rotten, including the thread, and there is no way to unscrew it. I put it back in the sink and screwed it up, everything works, but it keeps leaking. I was thinking about pushing something at a distance, in the shape of the letter C, about 2-3 mm between the tap and the sink, something to prevent it from flying around. If I don't come up with anything, I'll have to buy a new one. If I had known from the beginning that the cover had to be unscrewed, I wouldn't have knocked so hard and there wouldn't have been a problem. And it's probably not worth it to buy a new head, it's better to spend more and buy the whole battery, and they are not expensive.

I used the hole in the faucet that is provided for the drain plug. I took out the rod, put a 6mm screw there, quite a long one, made a washer from a thicker sheet of metal at the bottom and everything looks beautiful, and most importantly, the battery does not move.