Thanks for the comments gents.
Believe it or not I did have a good look at Gerrys SBS for the snatcher before tying - I've had another look since and I think I know where mine is different.
Midlander, you're right it is the ribbing that's the problem. I've tried allsorts, waggling the rib as I wind, going fast, the ones above were done slow and I tried to pick out the trapped hackles with a dubbing needle as I was working along and the results were better than usual. I won't be happy until they look like Cap n Fishys dabbler!
Snatch - I would happily swap any 10 of my ties for 1 of your buzzers! so until the ratio is down to at least 2:1 I will keep on asking
Cheers - Steve