Item locations at Ringworld Ledge:

1. radar part
2. box. Seeker is needed to lift this obstacle and Quinn is needed to get something from below
3. Quinn should climb ladder and operate radar controls to bring it down and activate catwalk. Now he can take a crucial part from radar interior.
4. guidance control device
5. grab gyro from ship and also get balloon and diagnostic display
6. fuel cell
7. Ledge Hopper with intact hull

Take bouth heroes to point 7 and repair Ledge Hopper using salvaged parts from all over the ledge. Jump in and pull at joystick. Here goes nothing ...