I don't think the Centrifugal Switch will work when just spinning the Motor by hand.
On a 240v device (the Heater Element), you can't just measure one side to ground.
That 120v reading could be comming from either L1 or L2...
Here's a way to tell:
Run the Dryer in the NO HEAT MODE
now check the voltage from each side of the Thermal Cut-Off to chassis (ground)
If there's 120v there, then the L2, Motor Switch, Heater, Hi-Limit, and Thermal Cut-Off are good.
If 0v, now you can check each side of the Heater Element to chassis (ground), ect...
It could be a bad Heater Relay on (or) the Controller Board.
While the Dryer is running in the Normal Heat Mode, if you could carefully measure the voltage across the Relay wires on the Controller Board.
Big Black wire to Big Red wire
0v = GOOD
240v = bad Relay or Controller.