I have bought a view magnifier (42459) to fit onto my PME51 prism finder. The instructions tell me to unscrew the eyepiece clockwise, fit the magnifier, then replace the eyepiece. Unfortunately, I cannot get the eyepiece to move. I have even tried using large forceps with paper wrapped around the jaws - and only succeeded in marking the metal ring. I wondered if anyone out there had had any experience of this procedure and/or any advice. I should be grateful for any help with this.