diberry - 3:14 pm on Aug 21, 2012 (gmt 0)
Isn't is also possible that these no-follow links are indeed something the algo always frowns at, but you can overcome it with other good signals - which is what unaffected sites are doing. Maybe with a more mixed link profile or something. So rather than looking for what's sending a "bad" quality signal, you should be looking for what "good" quality signals other unaffected sites have that your site lacks?
Just a possibility - you may have all the bases covered, I'm just throwing that out there.