Umm no, that won't work, that clip holds the lid on, hes better off running it as it is until he can order a new one, it will be fine with one missing, just make sure the rest are all equally as tight, but don't over tighten that will break the seal. Never had that happen to my fx5.... Did u just over tighten?
When I purchased a used FX5 it had a clip that was broken. Seller sent me a new one. It ran perfectly fine with the other remaining clips. So with that being said I think you should be ok.
F1 vet has not tried the super glue method. I say it's worth a shot until
you get a replacement part. If it works you will hold even pressure on the gasket.
mine did the same thing i had to buy a new one im going to buy a few back ups, the gluing it never worked for me i tried it but it still didnt seal right it just would break again