This might not apply to everyone but I found that using a tool, like a very small flathead screwdriver, can help in dislodging some of those tight parts. Take the part where the legs are locked to the chest plate in fighter mode, instead of bending the whole leg inwards to dislodge it, insert the tool in the gap and gently apply pressure to both the leg and the tool. Another part where it helps is with the swinging part of the shoulder joint. Using the tool helps getting the joint over the small hurdle which locks it into place.