I recently purchased a used P89 and did a quick cleaning before shooting the first time. While deep cleaning after shooting a few hundred rounds I noticed a slight amount of rust on shaft of the manual safety. My question is, what is the trick to disassemble the 2 halves of the safety? After close examination, it looks to me like I have to remove the rear sight and remove the firing pin blocker to get it apart, but I want to check first. I don't want to mess with the sight unless I have to since I've read that it can be a bear to even move it let alone remove it.