Sounds like a clutch spring tower or a clutch spring bolt broke and the spring is hitting the cover. Not far from catastrophic failure. Open, change, ride,
now if you're dropping the sump like
@Mittzy said, drop it straight. Clutch spring bits and pieces of aluminum in the front of the pan under the basket, clutch problem. Debris in the rear left screen area and no teeth; Torsional damper. Debris generally everywhere and signs of gear teeth the the noise is probably gear dogs too close because a circlip is on walk about. Just thinking out loud