[Canfred]

Hi Nick , perhaps not so rare but the best IIIf it is IMHO better than the S/Timer version since the body is too small for it.
It seems your's would benefit from a CLA and when this is done replace the half mirror. My IIIf was done we sourced the h/mirror from Edmonds USA but your tech would have access. Here is a picture of my camera with a little care your's will look the same. Enjoy your IIIf.