[Leica] Aging and dimming L'flex finders?

[simonpj at mac.com (Simon PJ)]

I use a Leicaflex, an SL and an SL2, all of which have been showing what
looks like de-slivering of the prisms for quite a while now. On several
occasions I have looked into having the prisms replaced, but decided not to
go ahead with the hassle and expense of sending the cameras away. The faint
de-silvering spots don't have much of a practical effect in use.

However, today I happened to be using the SL2 with 50 Summilux alongside a
Canon F-1 New with the 85/1.2 and noticed that the image through the SL2
viewfinder seemed to have a blue/green cast compared to the Canon. When I
compared the SL2/50 Summilux with a 50/1.4 on the Canon, the Canon appeared
to be brighter. 

It made me wonder whether the blue/green cast is a sign of deterioration of
the SL2 prism. My Leicaflex and SL both have the clear focusing screen with
microprism centre spot of the original Leicaflex. I noticed that whereas the
Leicaflex finder looks bright and without colour cast, the SL finder is also
blue/green like the SL2.

Are the SL and SL2 finders always a little blue/green? Or is this a sign
that they are no longer at their best, and it's time for me to bite the
bullet and send them away to get re-silvered prisms fitted?

All the best,

Simon.