Need advice Spotmatic underexposes a strip of nec close to the edge

Hi need some help. Has anybody seen on Spotmatic, SPII or SP F a straight or a diagonal underexposed band running by the edge of the negative that is on the side of speed selector (where curtains begin to travel)? This only happens at 1/1000. Please check my photos attached. Apart from that one underexposed band the rest of the negative exposed evenly.

I am wondering what may this be? It is clear that one of the curtains does something at the beginning of its travel.

I recently overhauled this Spotmatic and I deliberately overlapped curtains bymore than 1 bar (let's say 1 and a half bar) in an attempt to get fastest shutter speeds p erform closer to spec.

Thanks for all suggestions!

Alex

I recently overhauled this Spotmatic

Hi, when you say you overhauled the camera, what else did you do? The majority of Spotmatics I've run across these days tend to need a CLA, with shutter capping being a fairly common issue. Dried grease or lack of lubrication could cause uneven shutter travel.

Hi, when you say you overhauled the camera, what else did you do? The majority of Spotmatics I've run across these days tend to need a CLA, with shutter capping being a fairly common issue. Dried grease or lack of lubrication could cause uneven shutter travel.

Hi Dave, I completely tore down my Spotmatic, took out curtains, cleaned and re-lubed drum shafts, pinion shafts, cleaned all mechanisms, mirror cage and re-lubed everything that needs to be lubed.

I agree with you, I have seen it, when there is grease on selector gears or on curtain pinions the same shutter speed would be all over the place.