Mine pops off occasionally as well, got me a bit frustrated with my first 22. It's pretty tricky but it's a small price to pay for a valk that doesn't have obvious chunky legs in fighter mode, which is why I love them so much. They have a very sleek side profile and is probably the most successful 3D interpretation of anime magic in Macross so far imo. Would have liked for the backpack to collapse a little more in B mode but that may well compromise the fuselage in F mode.