My house has a conservatory dating from (probably) the 60' or
thereabouts. The roof is wired glass (maybe 16 - 18" wide) on
aluminium glazing bars. It's always been clear that the whole thing
leaks but, of course, recent rains have shown it up for what it truly
is (!). Presumably the glazing bar seals are history.

We've only had the place 6 months and have been planning to replace
the whole conservatory probably next summer, when most of the
essentials have been done inside. Meanwhile, it would be good to do a
temporary fix on the leaks.

The top section of the glazing is screwed down and I expect (haven't
looked) that this compresses a seal onto the glass. Although in
principle, unscrewing these and putting a new rubber strip would be a
fairly minor job, I suspect that most of the screws will be solid and
corroded, so attempting a proper fix may cause more problems than it
solves. How would anyone rate my chances of getting a reasonable seal
with a bead of silicone along each side...or has anyone dealt with
this issue in another way?

Cheers