I like your ribbon idea. I have a Jet 650CK, and although I figured out
the trick of pushing in the ring to fold it, it's not easy. The ring is
so stiff, it seems like there is a risk of ripping the bag, so I usually
remove the canister and pry the ring inward from above . A ribbon or
pullcord hanging from the ring would probably make it simple to pull in
from underneath. It's worth a try.