Head adjustment Danfoss-How to increase the small adjustment range?

Maybe a little theory will help you understand the principle of operation of this system https://www.pec.gliwice.pl/jak-dziala-glowica-termostatic
The first link from the shore, in case of doubt, please keep digging in the depths of the internet, because I don't see any irregularities.

This is a large adjustment range, although there are heads that do not allow the temperature to be set below +16 degrees (apparently there are such regulations), i.e. they do not allow the room to be unheated in winter (although sometimes even without heating (in winter) temperatures are higher especially when the sun is shining). They probably have some kind of blockade preventing it from turning completely to the right.

I have exactly the same problem: on 4 it just starts heating, basically the same as on 5, that is, I have no regulation. I only have an open/close adjustment. I have the setting set at 7. The only thing I can think of is that the valve is overgrown and on lower settings it doesn't let water out.

Maybe the valve is fouled - in which case you need to put the presetting on N for a while (say half an hour), don't put the head on and let the full flow flush it. If the head only works when you set it (the head) to 4, then maybe it has sensed that it has warmed up to the radiator. One important point. Heads should ABSOLUTELY NOT be covered with curtains, furniture during the heating season. If it is behind a curtain, it will sense not the temperature in the room, but that between the window and the curtain (and the heat trapped by the curtain does not go into the room, but is accumulated between the window and the curtain) and as a result, it shuts off the heating medium. The header MUST be SHUT DOWN. There may also be stone-covered branches (supply or return) which restrict the flow of the heating medium. One test can be performed. Remove the head, put it in the freezer for a while (say an hour). After taking it out of the freezer, immediately put it on the valve. There should then be a very high flow of heating medium. Also, it is worth observing whether the radiator starts to heat noticeably more strongly when the head is removed? If so, the problem is the head (not necessarily a damaged one - it could have been covered by a curtain, furniture, and this interferes with the operation). Heads MUST NOT be covered or obstructed by furniture during the winter season (also the radiator should not be behind a curtain or obstructed by furniture - i.e. curtains AFTER the sill in winter).