Rangefinder adjustments

[davesurrey]

I've recently bought a Bessa I (to complemenet my Fuji GSW690III) and bought a couple of rangefinders off ebay. They were cheap but cleary they are not accurate and the centre spots are very indistinct and not vertcally alligned. One is a Voigtlander and the other a Watameter Super. Does anyone know the procedure to calibrate either of them or where I can find out. Tried googling but got nowhere.
Thanks
Dave
:)

[payasam]

If the centre spots are indistinct, then the half-reflective mirrors need to be replaced. That is a larger job than mere adjustment.

[davesurrey]

I shpuld have been clearer and said the centre spots are "not very bright but I can still see a double image" rather than they are "indistinct".

So I would still like to know how to attempt an adjustment/calibration. I don't want to just throw these away without a try (we live in a far too disposable World) and at worst it will be useful for me to learn how to calibrate if I get a better one.

Again any help in pointing me the right way will be appreciated.
Thanks
Dave