The mirror has decided not to return to its completely closed position. The focus through the lens is way off. It is inconsistent between the top of the frame and the bottom (but consistent side-to-side). As well it is generally short-focusing: for example it makes you set the lens focus at 2'3" when the object is at 2'8". And of course the shot once developed is blurry if you rely on the reflex viewfinder. This does not seem to be a battery issue. M90 does not solve this problem. It seems as if something is just getting in the way of the mirror returning to its normal position. Is this an automatic "send to Nikon for a vacation"? Thanks for any ideas!