Hi Andrew, Your 2ndary shouldn't be 'tight' in the holder. I suggest you expand the brass fitting in some way or remove most of the overlap at the top, so that the mirror just 'sits' in & use a small dob of silicone on the back, before adjusting the clips. This should eliminate any 'pinching' effects.
PTN, my Meade 2ndary is simply glued to the back plate. No clips!
HTH.
L.