I have used a ton of these but never seen them mate so poorly. They are flat out too loose. The pins on the supplied JRC opamps were also very flimsy (much more so than normal) making this task even more difficult.
I have a recollection of having recieved a batch of 'special' MT sockets that were garbage.
They normally have a slight funnel shape at the bottom of the 'pit', which helps guide the pins into the sockets.
But these were flat bottomed,so the pins frequently bounced out or bent over instead of sliding in.
Wonder if they used that type, or similarly have a 'bargain betty' purchasing rep to cause such poor contact/insertion.
(Insert comment about 'race to the bottom' in mfg specs/build quality here.)
I never did figure out whether it was the hideously 'el cheapie' purchasing person we had at the time, or if they were indeed made that way for some (odd) purpose.
We did spend a fair amount of time 'evaluating' 'special deals' she got on some parts, IIRC.