"push on cup" sure sounds like CK Worldwide's "gas saver" brand of gas lens system. Here is a thread about it:
http://www.everlastgenerators.com/fo...clear-gas-cups

I second to check out what styles are normally stocked by your local welding supply. When you break a cup or collet or some part, it's awfully convenient to be able to get a replacement just right down the street, when you are having your gas bottle refilled. My guess is that your local welding supply won't have any CK gas saver parts in stock. If they can get them, everything will be a special order.

I finally found a welding supply that stocks the gas saver parts, they are not very close to me however. They are actually just down the street from CK Worldwide headquarters. They actually sent me to there once, on their behalf, to pick up a special order they placed for me:
Attachment 2443