Canon L3 - fungus in viewfinder

Hi All

Have just acquired a Canon L3.

Taken off the top plate to clean as much as I can, but there is obviously fungus on the prism inside the viewfinder. The unit seems to be sealed, so as far as I can see, there's no chance of treating it.

Anyone have any suggestions? The viewfinder is usable as it is, but would be much better if I can resolve the fungus issue.

Regards
Tim

Just an update.

Further research tells me it's on the part of the front element that sits at 45 degrees to the front window. Suspect this is the beam splitter, that can'e be monkeyed with, so I suspect I'm stuck with it :-(

Tim