I had to change out the light seals on my Wista 45VX (the ones where the rear bellows frame meets the body). I was getting significant light leakage along the frame. The foam can't be too thick or you can't close the camera, and it can't be too thin or the frame won't fit properly and the foam won't block the light. In case you have to change the seals on your Wista 45 VX (and likely other 45s in the lineup), here what I used.

The originals were very thin, about 1/4" wide and glued down. I don't know the original thickness because they were compressed with age. In the condition they were on my camera, I'd say max 1.5mm. The old foam seals came off easily but the glue they used was hard to remove. I used some Ronsonol and a lot of gentle scraping (but a different solvent would probably do a better job).

I tried some 3mm foam closed cell foam but that was much too thick. The correct foam is 2mm, open celled foam. The one I used (provided by the camera store that sold me the camera) was labelled "Sekisui #5782". Any 2mm open celled self-adhesive foam for light seals should do the trick. I cut it to 3/8th of an inch wide instead of 1/4". It has a very sticky self-adhesive backing but cuts to size and mounts fairly easily.

The new seals fixed 95% of the light leak problem. The last very tiny leaks are due to a poor glue join of the replacement bellows to the frame; I'm going to fix that problem with some black Permatex.