A single cracked panel seems like a two-bolt job, and sometimes it is. The part that catches people is the torsion spring sitting above the door, under tension, which has nothing to do with the panel but everything to do with whether you can safely take the door apart to get at it. Loosen the wrong bolt near that spring and you're dealing with a sudden release of stored force, not a scratch.
The other trap specific to older doors like the ones common in Tequesta is panel matching. Order a replacement section without matching the existing rib spacing and panel height, and you'll end up with a door that doesn't sit flush, binds in the track, or won't seal properly at the bottom. We'd rather you call before you order the part than after.