Thanks for the replies. I think I am probably starting too low on the feather and trimming the stem might do the trick. If not, I will post back with more details and some pictures. This is the particular fly that was giving me trouble when I gave up and found this forum:
I was using black hackle (I think saddle). Would neck hackle work better? I bought a half cape of grizzly, but don't have any black (and don't have the funds to buy another half cape). Are there cheaper alternatives?