I just put the front seal back on. The "track" is basically a "T" shape piece of aluminum with the top of the "T" facing inward. The seal just kind of snaps around the outside of the "T".
There is a wire (slide motor connection) which runs up through the center of the seal. The seal is the only thing that holds this wire in place. The connector at the top has disconnected twice when the seal came off.
There is no evidence that there was ever a screw at the top or bottom to retain the seal.
I think Seadog may have the answer. A couple dabs of RTV (assuming it will stick to whatever kind of rubber the seal is made of) may keep it from coming loose.
I'm not sure what to do about the rear seal since that end of the slide is right up against the refrigerator, and it would take either a Munchkin or a contortionist to get in there (a Munchkin contortionist would be even better