The wiper blade plays an important role. The head slowly moves across it, wiping any excess ink off, and it drains down to the maintenance tank. If it gets full of ink or dirty, it has a hard time doing its job. Wipe with a Q-tip and even remove periodically to rinse off if really dirty; just be sure to replace the same way it was with the curve going the correct way.
-Kevin Lumberg, Johnson Plastics Plus