Obotrol may be worn out, their might be an orfis in the system plugged up

Yes, it looks like steering valve, some name it orbitrol.

The big valve block under the steering column.

Sad news, but thanks for reply.

Everything works fine, except steering. When machine is stopped, handling need some strenght, when in move, you have to use two hands for handling. Lifting and tilting without objections.

Valve?

Well, pretty old one - 1991.
When there's no problem with traction, than, I think, that the steering valve simply reached it's lifetime.
It's hard to repair it, easier to replace.
The part No is 3525421200 - new, 3525421280 - refurbished.
The price - about 3300 PLN for the new, 2500 PLN for refurished.

If Fabric Number starts from 352B(...) then I think it is 352 series? : )

Which series of H40?
352 or 394?