The seller says the fingers are too small to see from that angle, which is true but leaves me wondering why they keep choosing it.

Have you seen any close view of the fitted fingers, even separately?

Only a photograph from the sample trial, where the lower contact has a small locating step; the new clip gives me no view of it.

That step sounds worth a close photograph before another arm-motion film.

We received two finger sets once with the same bag description. One pair had the relief needed by the sample and one did not. The packing photo showed only the backs, which looked identical, so it passed around our office without anyone asking the useful question. We eventually compared the contact faces with the agreed drawing and stopped the wrong pair being installed. Your step might be equally easy to hide accidentally. Ask for that face, not simply a higher-resolution version of the same distant shot.

Is the stepped contact specified in your agreed tooling drawing?

Yes, it is shown in the approved drawing, and the seller's close photograph now shows a flat contact instead; I have sent those two views back together.

That is a concrete mismatch to answer. Did they say the flat set was temporary demonstration tooling?

They said it was the set selected for packing and have now stopped packing it; apparently the trial pair went back onto their demonstration bench.

Useful catch. Ask for the corrected set's identity in the packing list too.

And keep the sample-handling check outstanding until they show the corrected assembly doing it. Finding the wrong fingers explains the photograph. It doesn't complete the demonstration you ordered.