watercooled RF ceramic power capacitor - need help

[cocolino]

Hello everybody,

This is not audio related but I thought someone around here might help and could tell me what manufacturer / type this part could be and could give advice about where it could be bought for a reasonable price.

The pictures below show a (literally broken) watercooled RF power ceramic capacitor of an unkown brand.
There isn`t any brand, logo, part number, value or anything printed on it.
All I know is that it`s from an induction melting machine (of a friend of mine).
From the service manual of the machine we figured the capacitance ought to be 4000pf.
The manufacturer of the melting machine said that exactly the same part isn`t avaiable anymore and that the replacement part would have 4500pf (of course they deliberately didn`t tell the brand).
The problem is the price they would charge for it is just insane.
I can`t believe that a device like this do cost that much. After all to me this appears to be just a ceramic tube with silver coated inner surface and with two silver coated water-connections on top of it (and a silvered tube inside, however it might also be that the water inlets and the tube inside are solid silver and not just coated, I don`t know).

Of course I`ve googled around already and also came up with some brands which produce similar capacitors but due to not having any information about the original part, I`m not sure if those could be a direct replacement for the broken one so I`d prefer to get exactly the same part if possible at all.

Any kind of help is much appreciated!