Looking for a source of leaks

Looking for the source of light leaks in the Zenit B. I think it's possibly coming from the area where the red arrow is in the image. There's a hole which was probably in the sibling machine the Zenit E light meter was attached. To the left there is also some signs of corrosion. So possibly linked. I can see a speck of light coming from this side in the view finder. I'll put some material in there and add some foam to the front of the mirror plate which is just a sliver of hardened material. It's that strip of material to the left of the red arrow. I suppose that was once rubber?
I could just through this away and get another Zenit body. But then that's a waste of material and money. I could also use this body to explore inside what is wrong with it further. The repair manual which I obtained from the Zenit users group has a list of options that are the common cause of leaks for this camera. The timer is jammed solid but I don't use that function mainly. Though that corrosion could've spread if that is what caused it.

I found my first camera

In the first half of the 1980s... My first electric guitar was an Ibanez ST55... my first synth was a Roland SH101... but the Prinzflex 500 was my first camera at around 1984. A rebaged Zenit B. Being the same as the Zenit E but without the light meter. Probably why I prefer manual cameras today.... Similar to the Zenit 3 in that is of a similar specification and layout. The cloth like covering gives it a vaguely Ashi Pentax Spotmatic look I think. Serial number 70118661 denoting made in 1970.

The Industar-50-2 3.5/50mm lens is quite a find. The number 2 denotes it's a M42 srew mount rather than M39. So I'm pleased that with an appropriate M42 adapter it can fit on any camera body. The non stepped aperture is changed from the outer ring at the front and the focus is by the external ring at the back. The lens serial number is 6968772 so from first two numbers denotes made in 1969.

After a test roll this has shown it has an intermittent light leak in the body. If it's not coming from the view finder I could temporarily gaffa tape the front and back seals externally and use the ever ready case. Though it could be reflected light coming through the view finder possibly. I was using this camera without a case on a sunny December day in 2008 since I last used it in 1986.