Hi all.

I really hope someone here can help me figure something out...

I have a Rolleiflex 2.8D, with a Schneider Xenotar 2.8/80 lens.
I'm experiencing a fair share of inward running field curvature from the centre to the outside of my frame.

My 2.8D is not pristine, and it had some work done on it...
Part of my question is, should there be a thin flat washer behind the front lens assembly. ie the part one can screw off the front to access the shutter blades.
I'm talking a very thin washer, if thats even the right term for it.

I haven't seen it on my other Rollei, be it a 3.5 Tessar lens. My friend, who fiddles with Rolleis, doesn't recall there being one either.
Taking the thing out doesn't really make a difference.

Example of the washer bellow...

I have yet to develop the film where I have screwed the front lens out a fraction ( about 0,5mm or less), just to see if there is any difference in the curvature.

I have originally calibrated my centre focus using a split screen and high magnifying loupe to get the centre right, which is sharp, no doubt about it.... however, the edges always focus in front of where the centre is focused.

Please visit a folder (LINK) on my ftp server, where I have two 1600ppi scans from my Imacon showing the effects.
Both images are focused behind infinity, and images were shot at f/5.6.

I live in Namibia now, a place even more backwards than South Africa, which is where I moved from (Cape Town more specifically). There are no decent or reputable repair shops around, and South Africa is filled with plenty of camera butchers. I don't really want to send my camera in. It's just not worth it. I'de rather try and find another Rollei at some point...

Can anyone confirm what the deal is with the washer, and whether it belongs there or not, and if it does belong, what the appropriate thickness may be.
The repair guy who cleaned and serviced my shutter a few years back, admitted to having lost the original ring, and replaced it with a new one. Whether or not the thickness correlates or not is my concern, and whether it is responsible for this curvature of field...

Anyways. Thanks in advance for the help.