As I'm still waiting for my next camera platform to get here -- don't get too excited, it's nothing new -- I decided to make an attempt of fixing the bellows on my Ansco.

Liquid electrical tape
One page advised using something called liquid electrical tape. I did a search and found a local dealer -- a marine supplies store -- and purchased their own brand of the stuff in a can. The liquid electrical tape is used to patch up electrical wiring, anything that has that flexible plasticky/rubber compound.

To apply it, I used swabs, which wasn't the right choice as it got fibres all over the bellows. I would probably use toothpicks or an art brush in the future. I basically held it up to the light to locate the pinholes, painted the area, checked again, and then did a second coat. I let it dry with the bellows open.

I might have put too much of the stuff on as the bellows now is more creaky when opened and closed. I've just shot my first roll after the repair so I'll know later how well my fix worked.

Update: seems to work

I got my first roll back post-fix and it looks like I solved my light leak problems. I can't post anything as I don't have my scanner in yet (yes, I've ordered a last year's model of photo scanner).