With all the doors unlocked, using the central locking feature, this morning, the fuel filler door would not unlock. Ambient temp was 39 degrees. Do the motors on these get reluctant when they get old?

I couldn't find the hook for manual unlocking when I opened the door in the trunk for the right taillight fixture; I guess I need to poke around in there a little more. If that's missing in action, is there another non-destructive way to open the door?

This is a 20-year-old car, that lives in a fairly low-crime area. I'm inclined to remove the "strike" for the lock rather than replace the motor/solenoid that locks it. Advice appreciated.