Re: SM shutter problem

[Bob Sperling <bowtie@abesr.com>]

At 08:07 PM 6/7/96 +0800, you wrote:
>Alex Hurst wrote:
>> 

>> I seem to remember reading somewhere that the cure for this is a small drop
>> of oil (but what oil?) where the long spring on the base of the camera is
>> tripped by the release rod (or whatever trips it).
>> 
>> a) Is this a cure?
>> b) What lubricant is recommended (remember I'm in Ireland)?
>> c) Should I even attempt this in the first place?
>> 
>
>
>I am having a similar problem with my IIIc where the shutter doesn't fire
properly, often at different 
>shutter speeds, and irritatingly randomly.  The frame ends up exposed for
about 5mm on one 
>edge, and the rest doesn't get exposed.
>
>I have just taken it in to get it checked out (or rather my wife who is on
her way back to London) - 
>will let you know what the reason/cure is on its return - but would also be
interested to hear what 
>the likely problem is.  Is it a common problem of the aged screwmount
mechanism, or just 
>coincidence?
>
>Nick Jackson
>Kuala Lumpur
>

Alex and Nick:

        Let's deal with Alex 1st:
                a) No
                b) Any watchmakers oil will do.
                c) Maybe.

        The flat release spring, unhappily, is not the answer to your
problem.  The shell must come off. Remove the 4 or 6 small screws from the
top plate WITH THE CORRECT SIZE drivers.  Remove the lens flange, making
certain to save and note the position of any shims, remembering to note that
the "O" must be reinstalled the the top position when the camera is put
together. Remove the 4 (or sometimes 5) body screws.  Some old model I
cameras have a 5th screw at the bottom of the lens flange, where the
baseplate fits.  Occasionally, you might find a flat reinforcing bar inside
the right side of the body, vertically on the right side (looking at the
body).  Not a problem; it goes back easily. Befire sliding the shell off the
body have a spring-closepin to hold the film pressure plate in position.
Hold the shell carefully as you slide it off the body, keeping a finger
against the pressure plate, and then clamp it with the closepin.

        I then take a cue-tip and using a little benzine, swab the top of
the shutter drum, avoiding getting any on the curtain itself.  Then use a
hypodermic and feed a SMALLamount of oil on the drum mechanism.  Also use
the benzine to clean off any dirt you see.  Reassemble, and you ought to be
as good as new.  Also, this helps shake out any film chips that may have
accumulated over the years.

        Now, Nick's problem is different.  Yes, part of the problem might be
general age.  It is possible that the problem is film chips.  Basically, the
disassembly is the same as above, except that there are some more internal
parts.  Nick, if you are interested, e-mail me and I'll give you more exact
directions.

Bob Sperling