What causes the op-rod to "jump" out of the track ? How do you fix it ?

Someone didn't know what they were doing and tried to install or remove the op-rod while the bolt was in the wrong position. You can install/remove the op-rod with or without the gas tube installed. You don't have to force anything, but it won't go together unless you have the parts in perfect alignment. I'd say that your op-rod is bent to the left, or has a twist just forward of the op-handle.

http://youtube.com/watch?v=0L1ZyaKO2Hs&feature=related

Field strip, very well done:
http://www.youtube.com/watch?v=wnjxnwCRz5k&feature=related

Kinda gay and some wrong info, but worth watching:
http://www.youtube.com/watch?v=OEsGENuj_NU

Not my weapon, just how it was explained to me.

Thanks for the info. Time to do some reading.