u/Gastly-Muscle-1997

5 years out of school, I finally got a job doing mechanical design work. Previously, I did a lot of test and production test automation work, so my skillset is unfortunately mostly related to EE and programming.
I'm still proficient with CAD, but not terribly fluent in GD&T. I still have decent heat transfer & vibration intuition (due to test), but don't remember anything about ANSYS. I don't know where to source parts beyond digikey, mouser, and mcmaster.
What resources exist to help jump-start and improve my ability to design mechanical parts and systems?
Are there any good free or low-cost GD&T intro courses or lessons out there?
How can I better find COTS parts, such as springs or gears or whatnot?

I'm looking to use some sort of clockspring or spiral torsion (?) spring to have a gear move to a specific angular position when the motor driving it loses power. The thought was to use something similar to a wristwatch's mainspring to push or pull it into the desired angular position. The gear moves up to a full rotation, nothing more, so I'm thinking something similar to a car wheel's clockspring could work, but I've never designed a mechanism with springs before.
It would be a light, plastic gear, about 4" dia. Any thoughts on where to procure that, or if that's even my best solution?
I'd appreciate any and all thoughts. Thank you for your time!