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Grimor

Kowa 8Z repair advice

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A friend of mine dropped his kowa 8z and although the optics seem intact, the focus barrel does not turn completely.
In fact from infinity to 8 feet, it turns smoothly as before, but at the 8-foot mark it locks completely as if it were the end. (from 8 to 5feet marks it lacks of 90 degrees of turn) 
I have tried to disassemble until I access the helicoid, but I cannot remove the focus ring because of the mentioned lock.
I can't remove the 3 tabs either because I only access 1 of the 2 screws each one has.
Any ideas to repair it?

IMG-20190809-WA0022.jpeg

IMG-20190809-WA0018.jpeg

IMG-20190809-WA0009.jpeg

IMG-20190809-WA0016.jpeg

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This may help you. Ignore the first part and jump to 4.00 minutes. From what I can see from your pictures you are halfway there. Usually, the next stage is to Unscrew the focusing helicoid backward. But be careful to feel when it will come away from the body and mark that location on both parts. Like servicing any lens, be sure to make marks on each helicoid part so when rebuilding you know where the helicoids screw together ... they are usually multi-threaded. When replacing final front ring, do not over tighten the ring, and do not over tighten the screws which keep the ring  in place ... this can lead to a stiff focus. Strange, but true.

 

 

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On 8/10/2019 at 3:50 PM, badbrush said:

This may help you. Ignore the first part and jump to 4.00 minutes. From what I can see from your pictures you are halfway there. Usually, the next stage is to Unscrew the focusing helicoid backward. But be careful to feel when it will come away from the body and mark that location on both parts. Like servicing any lens, be sure to make marks on each helicoid part so when rebuilding you know where the helicoids screw together ... they are usually multi-threaded. When replacing final front ring, do not over tighten the ring, and do not over tighten the screws which keep the ring  in place ... this can lead to a stiff focus. Strange, but true.

 

 

First, thank you for your response. Unfortunately, the lock of the focus ring prevents me from unscrewing it backwards. I have applied a lot of force by prying and it does not turn from that point. So it only occurs to me to unscrew it forward, but the tabs block the output of the front element. I am in a dead end. I'm thinking to drill some small holes in the focus barrel to be able to remove the hidden screws of each tab ...

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