My first time panel lining

This is my second gunpla I've built, but the first time I've attempted panel lining. I still have yet to add the stickers. I also stretched one of the arm sockets, so the left arm keeps arm keeps falling out. Any suggestions on how to fix that?

This is my second gunpla I've built, but the first time I've attempted panel lining. I still have yet to add the stickers. I also stretched one of the arm sockets, so the left arm keeps arm keeps falling out. Any suggestions on how to fix that?