Yes the servos tend to get glued in due to installing them rapidly after glueing in the mount.
You may have to pull the mount, remove the servo from that then glue the mount back in.
In other models they glue the servos to the foam and don't bother with a mount. In those cases you have to just pry the old servo out and then fill the damaged foam. (I use gorilla quick setting (Dries White) polyurethane glue to fill and cover a servo in plastic wrap, clamp in place to control the expanding foam glue. The plastic wrap peels easily from the glue. Install the servo using your desired method afterward.