Wheels & corners for Jelley screen doors

I have Jeld-wen screen doors and the leading edge has a gap of about half inch (vertical leading edge between slide door and frame). I can adjust the front most wheel pushing the door up and closing the gap, but not completely. The wheel itself seems to be in good shape, not so sure about corner/adjustment mechanism. Roller appears to be part no. 84-016, based on style and measurements. What do you recommend? New rollers and corner/adjustment screw?? Something else?

Here?s a pic of the gap on leading edge.

Hi Dave, thanks for you helpful response. I had removed the door several times to remove the roller and inspect. One subtlety, but perhaps an important one, is that the lift of the door with the adjustment screw is minimal and doesn't seem to stay put. Beyond the gap that forms at the leading edge, the door bottom scrapes slightly on the bottom frame, suggesting that the door really needs to travel higher. I can try longer screws but I am wondering if new rollers might be a good idea too. The doors are probably 15-20 years old based on the last owners of the house etc. Based on my roller dimensions it looks like Product Code: 84-104 is the right replacement part, the wheel size is 1 1/4 inch, or do you recommend the nylon version Product Code: 84-016? The steel would seem like it would hold up longer, but the nylon might be more quiet. We have nylon rollers on our Anderson doors at another house and they are whisper quiet and work wonderfully. thanks for your help
Siegfried