Junkers WRP 11 B Leaking Flow Regulator Valve: DIY Repair Solutions & Water Flow Adjustments

I am green in this equipment. Basically, at the beginning I had a different problem. Junkers did not start, the diode did not flash and this "ticking" or gas flow was not heard. I replaced the battery but then the flap, I thought that this driver was down but I started cleaning everything I could.
I started to turn the water flow regulator and when I turned it to the maximum, the water started to flow quite intensively. I noticed that the water is dripping from a small can I slightly opened it with one latch, blew it out and dried it.
Junkers works, you mow at the murder but you have to eliminate the leak and here a request for you. Can I fix it myself?
The leak is from the flow regulator valve, exactly from here:

I will add a video:

Pull out the flow regulator. Lubricate the seal / O-ring with silicone grease. Fold.
Sometimes it drips (but much less). Then dismantle the O-ring and go to the agricultural parts store for a new one.
In the first photo you have a microswitch marked with an arrow. Water stains can be seen on it. You probably have a damaged (worn out) water unit flap.
Photo from another model. But the item marked in the picture below is also at home. If it drips from there, it must be replaced.

O-rings should be replaced!

Thank you for the answers, I will try to use the tips and fix it myself.

I reheat the cutlet but I have the same problem with the same model, i.e. Junkers works but the flow regulator must be turned on all the time ("minimum water flow") so that it does not leak. I noticed that after removing the valve, there is some black plastic "O-ring", does this element cause a leakage? After disassembling the cover and trying to unscrew the valve to the maximum under pressure ("maximum water flow"), water is pouring very strongly from under the valve and the water pressure itself seems to be off my side. How to fix it? The house has 2 floors and the current low pressure of hot water in the shower on the 2nd floor is not overwhelming.

If it leaks, the O-ring must be replaced. You should search from the catalog (so that the dimensions are identical) or specify in the store what part it is and for which stove (or take the removed part to the store so that they can choose the O-ring).

What shop, plumbing? Because someone wrote here that agricultural ... I do not know where to look for this directory?