Hi Walter,
That's interesting because I've read in other places on this forum that the long straps are riveted in place. I'm talking here about the pair of fabric (with some elastic) longitudinal straps that disappear into the front of the frame but, on my car at least, are riveted to a 'loose' metal bar on the underside of the top about 3 inches back from the front frame section. Maybe my initial post was a bit misleading! I think you may be referring to the outer screws on the 2 front corners of the top to which a wire is connected.
Thanks,
Mark
Billericay, Essex, UK
Late 67 LHD 250SL