The -100 aircraft we flew for training was "bent" from a prior mid-air
Are you sure that it had been damaged by a mid-air?
The reason I am asking is that I flew the old 'Hoot' Gibson -100 and it flew just like you related. It always seemed like it wanted to fly sideways and it was impossible to keep in trim.
Fortunately we only leased it for a short period, about a month.