crick, also make sure to remove the metal thingie from the suction cup or someone's going to either bleed or scrape their watch somehow
Alternatives for the gasket? I'd only say castor oil but I'd rather use a watchmaker's oil if I was working on this stuff. You might be able to just use r/c pneumatic shock oil from a hobby store, those have rubber seals inside. Who knows, they might even have the same weight of oil as watchmakers use. I wouldn't necessarily recommend it for the moving parts though because it isn't blended for that.