"im not sure what your rep range is, but for me the sweet spot for arm growth is somewhere between 10-15, for me personally its all about maximizing the pump. try doing some kickbacks and some heavy skull crushers w/ an olympic bar"
I wasn't upgrading my weights on arm stuff until I did 14 reps and did great. After that I bought into the "go heavy or go home", stalled, got tendonitus. Now I'm back on higher reps and starting to gain again, glad to see that it works for you too!