I'd bet that you'd have a bit easier time with the areas under the ear and jaw if you add a few more skin stretching points. You'll be able to bring those areas up to a more manageable position and take out some "slack." Try moving your hand down from your sideburns toward your jawline after your first passes and stretching from there upward... your problem areas will probably be moved up to your jawline or above it where it's easier to shave.