I bought a second-hand Canon 100D after I got into photography this summer, and got to use a vintage lens that was still attached to my dad's Pentax ME Super (Asahi Pentax-M 50mm 1.4 SMC, a great step up from the Canon kit lens that came with the camera).
Now recently I got a decent deal on some vintage K mount lenses, €30 for a Asahi Pentax-M 135mm 3.5 SMC in pristine condition, some Pentax 28-80 3.5-4.5 zoom/macro lens with stuck diaphragm blades, and a Makinon Zoom 35-105 f3.5-4.5 MC. The latter is the lens in question...
I couldn't get the lens to focus, and it had signs of tampering (some half-stripped screw heads, and the metal was scratched at the back from not using a proper lens opening tool) but nonetheless, it felt smooth, has no scratches on any of the glass, and just seems to work fine. So I examined it and all seemed fine. The only thing that I can find is that clearly the rear lens element/group has been opened (slight fingerprints on the inside of the assembly), so I dissasembled and thoroughly cleaned everything but still no focus.
So my theory is that whoever disassembled this first didn't leave all the lens pieces in the correct order and thus it won't focus.
I've done my research but can't find any diagrams of this lens so I can't verify it either. So to anyone with more experience on the matter, does my theory sound right? Or what else could be at fault?
And does anybody have a way of doing or order of operations to go about finding the correct order of the assembly? Because there are 8 total glass lenses, about 5 spacer rings and a inner tube piece to center the smaller lenses, so that makes for a heck of a lot of combinations of order.