I have an Agifold with a non coupled rangefinder.
The camera is in really nice condition, but the rangefinder image is almost unusable, being far too dim. The front silvered mirror is actually not too bad, the problem was the semi-silvered beam splitter had lost most of it's silvering.
It was just dust lying in the rangefinder housing.

I managed to find a really nice beam splitter at Edmond Scientific for $15 or so - cut up it would have fixed a dozen rangefinders, probably.

Alas - I went all the way throught the checkout proceedure until it came to enter my address... and you can only enter a US state. Then I noticed the 'We can only ship to the US' message

Since then they have been spamming me with 'you haven't bought the items in your basket, why don't you complete your order?' messages...

Does anyone know of a source for such a 50:50 semi-silvered mirror either in the UK or who will ship here?