RB67 65mm C Lens: Sticking Shutter Blades and Oil Contamination
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This RB67 65mm C lens (floating element version) came into the shop with sticking shutter blades. While the effect may seem subtle at first, usually the symptom is overexposure while shooting outdoors since the maximum effective shutter speed may be as low as 1/30 second. I have had clients that used their RB67 for indoor flash photos and never realized that the shutter blades were sticking.
The only way to resolve this issue is a complete disassembly of the shutter to remove and clean the blades and the mechanism plates of the oil contamination. The online world is full of advice for cleaning leaf shutter blades with Q tips and alcohol but unfortunately this does not work (wish it did, it would save myself a lot of time and repair cost) so the repair requires a lot of labor and high cost to my client. Photo five shows the oil contamination on the shutter blade mechanism plate and this is why just cleaning the blades is a no-go.
This particular shutter is a 653 variant which was used 1970-1978 and is very well made. Only downside is that the blue steel blades do get oil contamination. In 1978 Seiko brought out the 791 series shutter with Dry Lube blades, no more oil issues but shutters did not have the same build quality.
Photo seven shows the final placement of the cleaned shutter blades. There is an order in which the blades must be placed and this shows the final blade with an upturned tab being installed. The video shows the test of the shutter blades after installation. The key to doing repairs is to constantly test the operation of installed parts. Much easier to catch a problem when the mechanism is apart.
