I'd stay away from mealworms as a staple since als tend to get obese (even babies) if fed too many.

I'd recommend hand feeding the baby that's having difficulties. Make sure the crickets are well coated with a phospherus free calcium supplement with vitamin D3. Sometimes a calcium deficiency will cause them to strike and miss. One of my madreans hatched out with one. It would hit the insect but not have the jaw strength to subdue it so it would restrike and its strikes got progressivly less accurate and more desparate. With 7 it took me awhile to realize what was going on. I started hand feeding him (if yours won't take food from your hand use forceps) well dusted prekilled crickets. I dust with rep-cal with vitamin d3. After about a week I started to notice an increase in jaw strength and after about two he started hunting on his own. He's still a little behind his clutchmates size wise but is doing great now.

Good luck!
Alice