I've had about 5 of the bl models, 4 of the prior models, and 3 GL models.
When Fuji added the Breech lock, the idea was that you could not take the lens off without opening the dark slide.
I don't know what you mean by the shutter jammed, because the shutter is in the lens, and it can be tested independent of the camera. (off the camera)
There is a lever that you have to use to charge the lens inside the back near the mount breech. You have to get to it with a stick of some sort and push the lever around the inside of the lens about 1/8 of the way around. Once you do that, you have to use the stick to move the second lever to trip the shutter. Again, this is lens off the camera.
If you can do that, and the lens fires, then the shutter is not jammed. I don't know how the dark slide affects lens shutter.
The breech lock (chrome button on side of lens mount on body). This was added because on the G model (first model) you could mistakenly take the lens off without closing the dark slide. The BL locks the lens, and you cannot remove the lens with an open dark slide, if it's working properly. There is some sort of interlink between the position of the dark slide and the lens lock mechanism.
I don't know what you mean by weak spring not allowing opening of the dark slide, unless there is an internal problem. A weak spring only serves to either NOT open the slide very slowly or not at all.
Common problem symptoms are, dark slide opening slowly, not opening at all from the closed position, or won't close at all.
In my terminology:
Open means the frame is not obscured so the lens can shoot through the frame onto the film
Closed, as in the slide closes off the entire frame, so the lens can be changed midroll.
I've had a couple of bl models that did not work properly, although the camera shutter worked fine (still puzzled on that comment).
On one the fabric came out of the tracks and jammed the opening partway.
My fix on "naughty" bl's.
Disable the dark slide mechanism if not working 100%.
Take off the chrome lock so the lens can be removed regardless of the dark slide
Do not do midroll changes.. That's pretty simple since only get 8 shots per roll..no more 220.
Use it like a G model.
Or send it to the guy who knows and can field strip these cameras in the dark. Frank Marshman. He's seen and CLA'd well over half of mine. In discussions about the dark slide, it's a difficult fix and not worth it. Lucky if it works at all.
Sure, it would be great if all these 40 year old cameras worked in every respect. In this case the mid roll change dark slide was a rather worthless idea in the first place.
The one I am sending him this week does have a nice, snappy dark slide, as about 1/3 of mine have had.
If you want Franks contact info, ask me please. He's on the East Coast, or $15 away by Large Flat Rate USPS. He's fair on price and timely on repairs.
