From: "Chris Reed"

The reason some people have problems is because they wiggle the wing.
This makes it almost certain that it won't slide into place. The key is
looking inside the cockpit to see that the pin on the end of the second
(port) wing is lined up with the hole in the first (starboard) wing. If
it is, all will slide into place (if you've greased all the pins).

Exactly!

A trestle for the starboard wingtip, and a belly dolly which doesn't
allow the fuselage to rotate, are probably the most useful things to have.

A trestele not on the wingtip but in the middle of the wing and a dolly that
allows a very slight wiggle around the fuselage axis works even better for
me.

Michael