Td5 braking distribution

Hello, my 90 td5, equipped with a non functioning abs at the moment (I’m working on that) is braking WAY more in the rear than in the front, which some times turns dangerous on wet roads.
I’ve cleaned the entire abs block and swapped the shuttle valve to a new wabco one, hopping to solve my abs light on problem (didn’t performed the bypass as I believe is not the problem and I really want to keep it original, specially when it comes to electrical stuff), but, despite not having a non functional abs system, I should have a normal power braking distribution, as in times I used to turn off the abs (by taking out the fuse) in certain circumstances and the braking power and distribution always performed well.

Some time ago (I mean over the last few years), braking behaviour came to the present situation.
New flexible hoses has been fitted all around.

Assuming the abs block is ok, the brake lines and flexibles too, where might be my problem coming from, since there’s no braking distributor on this spec model (it happens on the abs block, I believe)?
- It’s coming from the servo?
- From the braking pump after the servo?
- From the callipers?

Thank you, in advance, for your help.

I seem to remember that the TD5 has a split master cylinder for front and back ... have the seals gone on the front piston ?
Has it been reconnected arse-about ?

There’s two lines coming from it, separated front and rear, I guess.
I never touched the master cylinder and so I don’t know how’s inside. It makes sense that the problem could be there. I’ll study the internet about what fixes can be made there.

Thank you!

As it seems, there’s no repair kits available for master cylinders with abs, only for non-abs systems..

A oem quality new one will cost about 160€ and I’m not sure if the problem is here.
Is there any way to test it?
(Can’t see any leaks outside and the system is well bleed)

Thank you!