Chair bracket

[Christien]

I was getting into the car the other day and as I sat down, whump, out come the bolts in the harness at the left side of the chair, and the back (upright) part falls flat into the backseat. The problem is I didn't see what came out (i.e. bolt or screw) and couldn't find it in the car or on the ground, so I don't know what broke. Can anyone explain to me how the bracket is held on to the chair frame? I've tried all different sizes of bolts and screws, but I can't get anything to hold in there. The chair is, as far as I know, an original Recaro sport seat from 1972. Here's a pic of the bracket:



Is it just a question of not having the right size bolt/screw?

Thanks,
Chris