I just got a Jetwing Prime and while it's great with the tight joints and all, some of the joints are just too tight (the blue bits that form his back, specifically). I'm starting to see some stress marks and some are actually making me pretty nervous about moving these joints and transforming him. Any advice on how to loosen the joints just a little so they won't become too loose as well?

 

If you're nervous about the joint, I recommend using a hair dryer to soften up the plastic a little before moving it. Softer plastic is more pliable, and you're less likely to cause damage as a result.

Heating the plastic usually gets rid of those worrisome stress marks, too.