If they're nowhere near the strike zone, maybe they do need to change what they've learned? (Or relearn, correctly, what they were already taught).How do I help them with mechanics without changing what they already have learned?
Also, where is a good source of 10u mechanics that is somewhat universal?
Otherwise - see Northball's post.
I/R in the Classroom, Java's beginner's drills, and the slo-motion video of Amanda Scarborough on auto-repeat for ~ 100x. If after all that you still don't believe you could teach the basics, you should at least be able to know whether the mechanics your pitchers are using are effective, correct, AND repeatable.