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[Robert Bonn]

 The lens:  Pentax-A, 50mm, f/2.  Very clean, and aperture working fine.  
 
The problem:  The focus ring feels stiff when it turns, and the focus itself does not change.  In other words, you can turn the ring, with some difficulty, but

[rick oleson]

 If I recall correctly, Pentax attaches the focus ring to the actual focus mechanism by 3 screws that are reached from the front, behind the lens ID ring.  The screw heads clamp down on the ring so you can adjust the infinity position - if they get lo

[Glenn Middleton]

 I'm reading the problem somewhat differently, but I might have misread the situation. Robert seems to be stating that the focus does not change with rotation of the ring. So is the helical jammed and the stiff focus ring is due to the ring turning ag

[Robert Bonn]

 Thank you for these two responses.  I took the lens partially apart last night, and you're both correct.  
 
As Rick said, the focus mechanism has 3 screws, located behind the lens ID ring.  The screws were slightly loose, but just slightl

[Glenn Middleton]

 Robert,
 
Not having an example of this lens, I was just trying to find out if the focus ring had its proper limits of rotation.
 
These three screws, how are they spaced from each other? 120 degs, or are they in a single slot relativel

[Robert Bonn]

 Glenn, I'll try to answer your questions in the order you asked them.
 
1.  The three screws are at 120 degrees.  They're very small, of course, but they do have slightly pan heads, and in addition to that, they have small washers unde

[Glenn Middleton]

 Robert,
 
Ok, suppose I should do a diagram but I think this will put me in the picture - if a capital L represents the focus ring and a full-stop the screw, I picture you have this  L.  ie all the screws bear on the inside edge of the focus r

[Robert Bonn]

 Thanks for the information, Glenn.
 
I took another look inside the lens, and tightened down the three screws.  The focus ring is now jammed solid.  (I should add that while I had the lens partially apart, I wasn't able to rotate the helical

[Glenn Middleton]

 Robert,
 
Sorry I know nothing about Pentax lenses with this mount. Having worked on a number of other makes, I am sure that I could eventually get it apart. Still that does not help you solve the problem. You will have to strip the lens down so

[Bob Potter]

 Robert, I read about your situation.  I also have a 50mm lens in which I received from my sister-in-law.  She fell and broke her arm trying to protect her Pentax k-1000 camera when she dropped it.  After she recovered she tried to use the camera, but

[Chetan_dighe]

Hello Robert,
Just curios - have you solved it by now?
I have two pentax lenses - 50/1.4, 24/2.8. Both are fairly similarly built. I take them apart from both sides from time to time, to clean up the fungus. Haven't really got into any troub