Only identical valves may be replaced. At some points, valves are screwed directly into a block using screw connections. All fittings are used with a sealing adhesive (Loctite) on the factory side. When removing screwed connections, these must be completely removed and the adhesive residues carefully removed. Only then can the screwed joint be reused with new adhesive.
A calibration of the analog measuring channels is not necessary after replacing valves!