Wii U intermittently freezing & loud buzz from console.

I am getting this dreaded issue.  The Wii U freezes intermittently and there is a loud buzz/hum from the console.  The gamepad can be turned off, but I have to disconnect the power from the console itself.  It reboots fine afterwards... until the next freeze-up.

I have read that this is a known issue.  I have also read that Nintendo was hoping to fix this issue in a system update.  Has Nintendo indeed tried to address the issue in an update?  Here are some stats on my system.

Wii U Black

WUP-101(02)

system version 2.1.0 U

Attempting to perform a system update tells me that my console is up to date.

Any help would be greatly appreciated.