I've been trying to restore a Konica Pearl camera recently. The lens is rattling off the bellows unit. As this is a a relatively uncommon camera, I'm not optimistic but here goes.
The Hexar 75mm f3.5 lens assembly should be held onto the lens mount which screws onto the bellows diaphragm with 4 screws.
There are only 3 screws approx. 3mm across remaining. The fourth screw is missing resulting a displacement of 4mm across the plane of the focal length. The gap also results in interesting flare and light leaks.
This has really puzzled me: is there any way to close the seal between the lens unit and the bellows diaphragm?
I've never tampered with this kind of design - there isn't a single external screw which is easily accessible. Hence the aperture ring obstructs access to the rotating focussing mount.
Would it be worth pouring a small drop of superglue down the missing screw, or are screws of this size available anywhere? This camera has been CLA'd (probably 1960's) and is mostly user-operational otherwise.
Micro-Tools has screws up to 2.0mm diameter; McMaster-carr ( http://www.mcmaster.com/ ) has most metric sizes from 1.0mm up in a variety of materials and styles (this is a good place to buy tools & stuff, by the way, and they ship instantaneously)
I would avoid super glue unless your alternative is the dumpster, as it will likely make any future service more difficult.