Any tips for getting pieces to stay? I keep seeing reviews saying how "sturdy" the kit I'm building is, and there are several pieces I can't get to stay for the life of me. I would love it if there was an adhesive akin to superglue except not totally permanent. Is there something like this in the hobby space that's a go-to?

Also, there's a piece in particular that I can't get to connect at all. Shown here in my RG RX-178 Mk.II Titans, the step at the end of the second row (using pices F15, G1-20, and A6) I can't get the completed piece to attach to the waist. Looking at the finished product this appears to be a weapon holder. I'm so frustrated I'm considering skipping it entirely.