The part number for the rubber ring you are looking for is 126 683 01 57, taken off the ring on a panel I have in the spare box. I also compared a US to Euro (I have an example of both) and both have the same part number.
I experiemented with the Euro panel and found that the ring is attached using only contact cement. I also checked PartsShop and FastLane, they do not stock the part, but that doesn't mean Phil can't get it. Might be worth a call to Phil first, see if he can source one. There are enough 126 owners here who could probably use a replacemnet (myself included) and if Phil can source them and get them in FastLane I bet they'd sell like hotcakes.
There is a chance they may only come as a complete assembly though
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.