Well, mixed feelings today... My Zenitar-ME1 lens arrived from my favourite seller in Ukraine, and it's absolutely "as new". However, it has a sticky diaphragm
I can see a little oil on the two blades where they cross over, and I'm sure that's the cause. Now I have to decide whether to return it for a full refund (which I'm confident I'd get), or negotiate a discount and service it. I've worked on the six blade Zenitar-M 1.7/50 which is supposed to be almost identical, but of course the diaphragm mechanism has differences, including an electro-mechanical assembly coupled to contacts on the mount.
If this were a $50 lens, I'd be straight into it
But given what I paid for it, and the condition it's in, I can't deny I'm nervous about attempting the job myself. I have a few days to decide, as the seller is away for a couple of weeks - and right now, I'm thinking I'd like to keep it and service it.
It's very unusual for this seller to send me a lens in non-working condition. I suspect it may have been freshly serviced by his lens technician and working OK when he shipped it, but lubricant has migrated to the blades while it was in transit.
I'll muse on it further