There's a glass block window in my basement that has a 22x8 vent in
it. The vent is opened or closed by a crank that operates two glass
panes. This is common in older glass block windows. However it is very
leaky, and the mechanism becomes useless soon, leaving the glass
frozen in a slightly open position.

Newer windows have a hopper vent, which has double-pane glass and a
simple hinge mechanism, which seals better and lasts longer.

If I had a 22x8 hopper vent, I'd gut the old vent, leaving the
aluminum frame in place, because it is screwed to the glass blocks
from the inside (how this is done I can't imagine). Then using
suitable wood blocks, I'd create mounting points for the new vent
mechanism.

However it appears that vents are available only in 16x8. What then
is a good way to do this? Even replacing the vent with glass blocks
would be difficult, because it would involve removing the frame.
Thanks.