I want to make sure I'm doing this right... The turtles get up there to bask but I'm yet to see them extend their legs, tail and neck all the way out how they normally should... Is it too hot perhaps?
The screen is probably blocking uva/uvb rays. Im not sure how far apart the squares need to be but I think it was like 1/2 inch or something like that.Its posted a few time around the site.
The screen will filter some of the UV. Depending on what kind of UV bulb you're using, you may or may not want to remove it. If you're using the 10.0 UV bulb, you may want to keep the screen.
Otherwise your setup looks nice. The gravel may be a problem if it's small enough for your turtle to eat. They can get severe impaction from it. You can put a thermometer on the basking platform to see what the temp is.
The gravel is very dangerous. There have been too many threads on here about turtles who ate it and didn't survive. It's heartbreaking. You shouldn't take any chances with it - get it out of there as quickly as you can.
That spiral UVB light gives off 3% UBV? If so, I'd move it closer to the basking area. Somewhere in the range of 88-90F for the basking area temp is good. Check it with a thermometer.
"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-
The reptiglo 5.0 gives out 5.0% of its light as UVB. That's a good bulb and you should be fine where it is, but you should probably remove the screen lid if you there's no risk of the turtles climbing out or other pets climbing in. The 50w zoomed spot lamp sounds good too, just check the temps after you get a thermometer.