I have a Whirlpool belt drive washing machine that gave up spinning. It is only about 2 years old. I replaced the splutch kit, the belt, and tested the door switch. Everything appears OK. All other functions work fine so I don't think it is the transmission (maybe it is..). Everything underneath looks to be in great shape. It is not that little actuator on the bottom that changes the drive. I've watched it work several times. I cannot figure out the diagnostic codes.....
This washer is in great shape and I hate to give up on it! Can anyone help??

Have you located the tech sheet? It gives info on automatic and manual test modes and how to read error codes. The shifter you have watched move several times also contains a sensor telling the MCU the RPM of the basket, and that portion may be faulty. Those machines also tend to break a wire (red?) at one of the zip-tie clips near the front of the tub that can keep it from spinning.