my 90mm (which is nearly the same as the 100mm) has some fungus inside. I would like to take out the rear lens element for cleaning. has anybody the "MAMIYA PRESS UNIVERSAL LENS REPAIR MANUAL" and could give me some advice how to disassemble the lens? the shutter is fine, so no need to touch this. thanks in advance. a link to a .pdf version of the manual would also be very much appreciated.