The immovable stationary panel(s) of a wood-core sliding patio door system should be secured to the jamb, however, over the years, if not secured properly, it can work its' way out of the jamb revealing an air gap.
These panels are usually kept in place by angle brackets at the top and bottom of the panel edge where it meets the movable sliding door.
Often, these angle brackets are missing, broken or bent. Small galvanized angle brackets found at the hardware store may not be a sufficient replacement to secure the panel. We recommend using brackets supplied by a sliding door manufacturer. They do not necessarily need to be from the specific manufacturer of your door.
Some vinyl systems have nylon brackets where the panel meets the jamb at the top and bottom on the room side of the system. These often break and, if they are from a "Republic" door, they are no longer available and must be retrofitted with a stronger alternative.
Once the panel has been re-set in the jamb, install the brackets to prevent a recurrence.