Amana Washer will not agitate

The washing machine recently stopped agitating. It would go through the cycles, but did not spin. Never repaired a washing machine before, but I checked the belt and it was worn and ripped apart. I replace the belt, however I’m concerned because it appears to be too loose. I can adjust the motor to tighten it up because the motor is mounted to a frame. There is a spring idler attached to the opposite end of the pully that seems to create tension. As I rotate the belt the tension increases and decreases. When the tension decreases and the spring stretches, the belt seems too loose. Should I replace the spring or is this normal?

***** Update *****
Changing the belt did not solve the problem. Right now the tub fills with water, no agitation, does drain, no spinning. Help…