so I bought a Bronica S2 that had no been used the last ten years. Being well aware from tons of comments on the net that it uses foam to position the mirror and the focusing screen, the first thing I did yesterday before going use it, was to check that. It's very easy, yet a couple screws were tricky to put back. The fix is explained at many places, and for the mirror the more detailed seems to be there: Bronica Z, D. S, C, S2, S2A, EC, EC-TL, and EC-TLll besides a couple good screwdriver, I used ethanol, cocktail sticks, swabs and paper for cleansing, a bit light cardboard and masking tape for prophylactic protection inside the body, glue to hold non-magnetized screws, a mobile phone screen suction cup, and self-adhesive 3mm open cell foam. as I take shots for my own archival, I think it may of interest to others. So, if you get an old S2, don't hesitate, it's easy. See: remove the viewfinder, and there are four screws holding a frame over the focusing screen. The two screws near the focal plane do also hold the bracket for the viewfinder. These four screws have same size, and are non-ferrous,as I couldn't hold them on the magnetized tip of the screwdriver, but it's no problem. under the bracket, a brass spacer and a tiny shim under: this is how the foam under the frame had turned over the years: I dipped the frame first into a dilution of soap, and rubbed away some of the stickery gum, but rinsed and dipped it for a while into ethanol removed the sticky gum by the edges on the top of the matte glass with a piece of cleaning paper with a bit of ethanol, and washed the matte side under tap water without touching it: the fresnel under the matte was clean. the edges on the body required some ethanol and gentle scrapping stick and swab; Put focusing matte, fresnel and retaining frame aside, and now the mirror. I position the body upside down at an angle, so the mirror is horizontal: put a piece of thick paper for protection on the mirror: four screws hold the mirror frame. The two upper ones are shorter and non-ferrous as I can't hold them with the magnetized screwdriver tip: remove the mirror frame and then the mirror: so the mirror plate with the three foam pads: they left a mark on the back of the mirror: by just touching with the finger, the foam crumbles: I use light glue painter masking tape to protect the opening where we see the ribbon in the top middle and the gap between mirror plate and body, so to avoid foam rests get inside: I had to use to ethanol and rub gently with a screwdriver tip and a cocktail stick: cleansed: foam. I have some kit with different kind and size. Under the mirror I think 1mm could be enough. But open cell foam with be pressed well even if thicker (reasonably). I opted for a 3mm open cell foam with an adhesive side. Used it under the mirror and under the frame of the focusing screen: new foam pads: next step could be a bit tricky even if the foam is only 1mm. This new foam pushes the mirror up, and the lower edge of the mirror frame is rounded and catches under the mirror plate. So I start with the two lower screws, put loose only, they will keep the frame on place but allow for sliding the mirror into correct position: the two lower screws are easy, longer and can be hold on magnetized tip of screwdriver. But I found the two upper ones finicky to manage, they screw under the mirror frane, not on the plate, but on a tiny support that rotates around an axe: at the same time, the mirror under the frame must be slided down into the lower edge. The small rotating piece for the upper screws must be aligned and nor move when putting the screw back. Here I used a nail for positining: in fact when that small rotating part is correctly aligned under the mirror frame, by pressing the frame, there was a slight "click", so holding pressure on the frame with a finger, I could screw back. But the damn screw isn't hold magnetically on the screwdriver tip. Used a drop of liquid paper glue, which is very light but enough for the purpose, to hold these screws: Of course the mirror, which is pushed up by the new foam, must be correctly slided down, for the frame to set in place. But that's easy, I just used a small suction cup for mobilphone screens: mirror back in position: then the frame of the focusing screen with new (3mm) foam: that's it.