Any recommendations on what kind of foam (and where to get it from) would be suitable for replacing the one in the mirror box (the one the mirror rests upon when in upper position)?
I replaced the foam on several bodies, both M and K mount I cut up him in a carpet of mouse (tapis de souris) and gluing with cyanoacrylate glue The density and color are appropriate. It is necessary to be attentive, but this is not very difficult : http://pesro.wanadoo.fr/krg/Photo/bricolage.htm#mousse I use a short stick (toothpick), to put a minimum off glue.
Michel

