Microsoft Natural Ergonomic Keyboard 4000 V1.0 KU-0462 Some Keys Not Working

• Connects to the PC and most of the keys were responsive when testing.
• The keys I found not responsive is Z, C, 1, 4, F1, F4, F6, Mute, and Volume Up.
• This keyboard probably requires a new board ribbon inside.
• Shipped out within 1 business day.