I put in the dimensions to figure out the size of your tank and it's equal to a 25 gallon. So, for right now, I would use a 40 watt household light bulb. Did you take the red bulb out and replace it with the household bulb? If so, do you notice any difference in how they are acting?
The UVB is the coil bulb that you're using now. That's the one that needs to be replaced. Unfortunately, you'll need to get the tube bulb and holder, would stay away from the Repti-GLO, would get either the Arcadia 12%
http://www.superpetsdirect.com/products/Arcadia-D3%252b-Reptile-Tube-12%25-UVB-Light.html I really would recommend that you turn the coil UVB off for at least a few days to see if you notice a difference in the sickly one. Even thought he eats on & off, the behavior that you mentioned in your first few posts are very concerning. The other baby may be acting ok right now, but the coil bulbs are very dangerous as they don't put out the right amount of UVB and actually produce UVC's which are very serious.
Minipumpkin is right, the reptile carpeting is expensive. NON-adhesive shelf liner is inexpensive, comes in lots of colors and patterns and is easy to clean.
How many crickets are each of them eating a day? Are you keeping the babies well
hydrated? Did you get a chance to look over the list of greens on this site?
http://www.beautifuldragons.503xtreme.com/Nutrition.html