Go back under the car with a mechanic's stethoscope. If you don't have one, use a length of plastic tubing, one end held to your ear and the other near a suspected source of squeak. You might be able to narrow it down.
Spraying a suspected joint with something may stop the squeak and help with diagnosis, but it won't last. I would use a silicone spray instead of WD-40 just because I know it won't hurt any rubber. Water would probably work for diagnosis, too.
Spraying a suspected joint with something may stop the squeak and help with diagnosis, but it won't last. I would use a silicone spray instead of WD-40 just because I know it won't hurt any rubber. Water would probably work for diagnosis, too.