For the past several months or so I CANNOT get my biceps stimulated correctly. Because of this my bi's have plateaued tremedously. I used to be able to stimulate my bi's just fine when they were smaller. I think I have subconsciously altered my form, and now I don't know what the hell to do.
Yesterday I spent 45 minutes trying to find an exercise that would stimulate the bicep's brachii, the area of preferred stimulation. Instead, I am stimulating the brachialis and/or the brachioradalis... pretty much the lower outer bicep and upper forearm.
I've attached a picture to illustrate what I mean. The blue area is what I want to feel pumped while I am working out. The area in red is what I am feeling is being worked. That area gets pumped during the workout (not the bi's) and that area is sore the next day. I haven't had actual bi soreness for more than half a year now.
Please note that I am not a newbie to this, I've been training for over 4 years. But I need to know the proper FORM for bicep training since I seem to have lost it. Please give your opinions on best exercises, form, tempo, amount of sets, reps, etc. What could I be doing wrong to get this effect?