Pentax Spotmatic refuses to open aperture after metering

I just bought a Spotmatic SP and a Super Takumar 55mm 1.8 at a flea market for $40. The camera is in fantastic condition and appears to work flawlessly, except for one thing: the little plate at the bottom that pushes in the pin to stop the lens down for metering doesn't return automatically.

I can push it back manually, and it's stiff when I do that. Sometimes it works, but most of the time the camera stays stopped down after I push the metering button.

Is this a common problem with Spotmatics? Is there any way I can fix it, and if not, would a CLA be likely to fix it?

Hello,
when you switch on the meter, the plate is moved forward and the lens is stopped down by the little pin on the rear of the lens. If you switch off the meter or if you release the shutter, the plate must go back to its original position. If this is not so on your camera, it should get a CLA. You also should have a look on the light seals and the mirror damper/seal since they may be now over 40 years old.

There's gunk on the mirror, but it drops down fine, and the seals seem intact enough. I guess it's going in, then.

Hello,
I have used Eric Hendrickson for CLA's on my Spotmatics and he is great, very fair prices. He is a Pentax tech. Pentaxs.com

Chrismat said:

Hello,
I have used Eric Hendrickson for CLA's on my Spotmatics and he is great, very fair prices. He is a Pentax tech. Pentaxs.com

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+1

Eric does excellent work.