Originally posted by marcusBMG
I have the same thing with my helios 44 (original silver 13 blade version). O ring sounds good - where do you get one?
I'm just looking on eBay UK right now... will post what I find here shortly

---------- Post added 08-22-2015 at 08:02 PM ----------
Right, got it!
I'm not sure if it's OK to post links here, so... in ebay uk, search for "38mm x 4mm rubber o-ring"...
My thinking is, a ring with 38mm inside diameter should stretch and would be a good, neat fit around the neck of the lens, and at 4mm thick it should easily cover the cut-outs... Looks like there are plenty of other diameter / thickness options available from other sellers.