Have any of y'all changed the focus screen in your Rolleicord 3? I got a fresnel with a splitscreen on eBay but now that I have the hood off, I can't figure out for the life of me how to get the old screen out and the new screen in. There are leaf springs on the bottom (matte) side of the glass that hold it in from that side, and a frame of sorts that holds it in from the top. I found a repair manual, but wasn't able to make much sense of it since the PDF was rather bad from being a copy of a copy of a copy. Thanks!