Refurbished hydraulics - on cars - hmmm that can be a tricky one. On aircraft (particularly military aircraft) there is a wonderful thing called scheduled maintenance where things get taken off - checked and repaired. Having been part of this - I can say that that is where components get saved before something gets to a non-repairable stage or corrosion sets in.

From my experience of hydraulic components on cars I would say that if the part is corroded near or on the sealing surfaces you may as well chuck it. I have recently, for example, spent a lot of time trying to reseal the calipers on my W123 but they were too far gone.

But that doesn't necessarily mean that your MC is dead - if you can do the work yourself you could rebuild and test it. Failing that if you know of someone else who can why not get their professional opinion?

EDIT ah ha seeing what you've just written I'd say bleed it first!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!