OK guys...
I have had my shipments of Rambo's delivered (well 1/2 of them, still a load in UK customs)
I checked all what I have and most have the loose shoulder joints but with enough futzing, it can be sorted......
Which led me to think.... W T F is wrong with the shoulders in the 1st place.... so I took the decision to cut mine up!! As it was my own one, I just glued back and it looks fine....
Here is what I found!
zoomed out view
from back
under arm
The tightening of screws don't do anything.... make the pics what you will.
All owners of this figure are in the same boat, I opened up because to give you an idea of what the problem maybe, I think its best solution is to keep futzing until you get the desired look!
Took me around 5 mins of futzing to get mine looking like carlosaraya's below.