I had bought this camera some time ago. Did not get to use it after cleaning and lubricating. It needed very little adjustment except for a little curtain tension tuning. The 4K is almost the same as the 4 except that it has a lever wind. The lens was one of the “bad” ones I got from Ukraine for less than $2 a piece. It was full of dirt fungus and dried up grease. It was not focusing to infinity either. I dismantled the lens and cleaned it with Petrol [Gas] first and then the glass with Ammonia and Peroxide mixture with a final clean in filtered water. Wore clinical inspection gloves to keep the glass elements clean. Lubricated the threads with new grease and mounted by trial and error to the correct groove. It has six entry points, only one of which would focus to infinity. Tested the focus on distant and nearby objects with translucent plastic film on the film plane with the shutter open at B. Adjusted the scales for the aperture and the distance marks and tightened the set-screws. This also takes some trial and error and patience. Today was a very cloudy day; the light was dark. I took most of the pictures between F/4 and f/5.6 with the shutter at 1/125 sec. Film used was ORWO UN54 ASA100 processed in homemade brew. Here are some samples.