http://youtu.be/uWnjeCH6bic
There is great value in doing reps at lighter weights. I recommend that when you are struggling with a move and you figure out a specific piece of that move that you need to work on that it is time to go down in weight and drill that specific piece.
For instance, I struggle with keeping my back from bowing in the jerk. As the weights get heavier, I bend my back and (unsurprisingly) it hurts. To remedy the problem, I dropped the weights down until I stopped making that mistake and then slowly tried to add more weight back on. If the problem reappeared, I dropped the weight back down.
There is merit in trying to fix problems while staying at a heavier weight. But if it is a persistent problem (I’ve been bowing in my back for quite some time) then maybe dropping the weights down is a good idea.