Here is how to reverse the F2 Bighorn.
1. Remove the spool by placing your thumbs on the small black/grey rubber, and push, the reel should come off.
2. Remove the rubbers on both sides of the reel (drag knob and axel)
3. On the axel housing you will see a little notch, you will have to remove this one with a small Alan key (hex wrench)
4. In the drag knob you will see a screw, remove and twist off drag knob completely
5. You will be able to pull the complete drag housing apart and will see the inside of it (cork, brass insert etc.)
6. Remove the brass insert and the axel out of the axel housing
7. Inside you will see a ribbed 'insert' this is the 'one-directional bearing', you can gently push it out, in most cases it will slide out
8. Turn the bearing 180 degrees and put it back in; make sure you take it out in such a way that it doesn’t fall, if you by accident drop it and put it back, I guess you have a 50-50% chance you changed the retrieve : ))
9. Now your reel is the opposite retrieve
10. Place back the axel and brass sleeve, and slide back on the axel attached to the reel housing
11. Twist on the drag knob
12. Screw in the tiny notch/screw in the axel part of the housing
13. To set the drag: tighten the knob in such a way that if you turn it from 5 to 12 counterclockwise back to 12 you should feel the drag come lose (at 12 is where the screw will be stopped by a peg and will be your drags range, let's say)
14. You can set your drag a bit tighter or looser by placing the screw at 5 to 12 or let's say 10 to 12.
15. Put back the rubbers
Please make sure you take it apart above a towel, the screws are pretty small and fall and bounce everywhere.
Good luck