I picked up this Pentax S3 along with a Stereo Realist and an Ikophot light meter for $100. I purchased it from Paul Dawe who was selling it for Ms. Eleanor Muise. I laso purchased a Rolleicord Vb from her as well. This camera with its film door latch that needs some fixing. Otherwise, it is a beautiful mechanical camera.
Serial #: 516389
Lens: Korinar Auto, 1:2.8, f=135mm, No. 1604108
Mount: M42
Pentax S3
Images below show the filmdoor latch that is bent resulting in the door not latching properly. A slight bend with a screwdriver and the filmdoor now closes.