This photo shows the inner surface of the end-ring after machining through the laminated core (1 cm/0.394 inches from core end): this revealed the faulty region as shown.

At the faulty end, the end ring virtually "fell-off" during the machining process.

A complete inspection revealed:

• 6 broken bars and spark erosion
  
  
• A number of partially broken bars
  
  
• Blow holes in the die casting bars to end ring region