After looking at the transformer label, we like to get inside (do this with the power OFF!). Transformers come in all shapes, sizes, styles, and levels of quality, as you can see here. We're looking for:

• Ungrounded secondaries
• Improper neutral connections
• Poorly grounded secondaries (meet NEC, but not optimum)
• Loose connections
• Overheating connections, coils, or conductors