Xantia brake doseur high internal leak rate

[naxmon]

Dear forum members,

warm greetings from our Xantia community here in Colombia (South America). We are more than 200 proud Xantia owners here, trying to keep our cars running as best and original as we can.
Today I wanted to open this topic as we are starting to face a complex problem concerning brake doseurs. I apologize in advance as I know there are a plethora of posts dealing with brake doseurs but I wanted to open this new topic as the failure rate of the doseurs here in my country is very high now.

The problem consists in very high return leakage on our doseurs, thus leading to low pressure values on the suspension side and very frequent "tick" rates (~2-5 secs).
After correcting problems in the pressure regulator units, cleaning, checking all hydraulic components, the problem is still there.
We have also tried to overhaul our doseurs: changed all seals (from citroen dealer), cleaning thoroughly pistons, casing and so on, however the problem persists. We are fearing that tolerances have become too wide in our doseurs, leaking a lot of LHM flow to the return pipes.

The only thing that we haven't really checked/validated are springs: the 2 identical small ones going in the same axe of the pistons, and the 2 bigger ones. I wanted to ask you guys if these springs could cause such leaks? In any case, is there a specification for these springs? I couldn't locate any information on any of them...

Aside from that, I have sent my doseur to someone from my family in Germany, in the hope that maybe someone in Europe/UK area can test it and might be able to find a solution. As I posted in the title of this topic, we are more than 200 people in Colombia and probably 50 of us are dealing with the same problem, as there are no new parts from Citroen or others, we are fearing the likely death of many of our beloved Xantia's if this remains unsolved.
However, having searched this and other forums I do not find any information on out-of-tolerance doseurs with such a rate of incidence as we are facing here. This leads me to think that we might be thinking and pointing in the wrong direction.

If someone could give us any lights on this, it would be greatly appreciated.

Regards from Colombia,

Nicolás