Wow - someone else with an Ambrogina!
The seal is a square section O-ring. If you take the cap with you to someone who sells O-rings, youll be laughing. I cant remember where I bought my 6 spares, but they cost me next to nothing. Id offer to send you one, but I bought them 20 years ago (ish) and time has not been kind to them. They are junk - slightly hard and riddled with cracks... I suspect a decent sized O-ring will work too. Youd need to get one that doesnt fit into the groove in the cap though, I think.
There is no LED on mine, it is a neon ;) I dont know if the standard-ish neons you get from the likes of Jaycar would fit, but Id give it a go.
My Ambrogina suffered a terrible fate - got left on (well, it got pushed back into a corner and the switch got pressed on by the cord...). I dont know who makes the heating elements but theyre good. The element never blew, but the machine itself split!
So mine (red) has a 50mm wide bare aluminium stripe up one side where it got TIG welded >:(
Still works, but it is more of a historical curiosity in the KJM household.
Wow. Its been at least 10 years since the word "Ambrogina" has been uttered around here!