Multifort

A dried Aquadura cork seal explains a leaking vintage Mido

The cork element in an Aquadura crown swells slightly on contact with water, which is how it seals. Stored dry for decades it shrinks and hardens, and the watch loses its water resistance. A period Mido that fails a pressure test is very frequently a watch needing a crown service, not a watch whose water-resistance claim was never true. Report it as a service condition rather than as a specification failure.

Redials are the characteristic vintage defect

Mido made a great many watches at modest values, which is the exact condition in which refinishing pays and counterfeiting does not. Printing that sits on rather than in the surface, a minute track that stops short of the edge, and Mido lettering with modern proportions are the indicators. This is a restoration finding.