OK the latest round of updates got rid of the garbled terminals at all resolutions. Terminals are back to normal when gfxpayload is not set in the 00_headers file. When gfxpayload is set to keep I just get a flashing cursor in the tty windows. This occurs at GRUB_GFXMODE=1280x800x24, GRUB_GFXMODE=1280x800, GRUB_GFXMODE=1024x768 and GRUB_GFXMODE=800x600. So I guess the bug is still there as I cannot access the tty other than at the lowest resolution.
OK the latest round of updates got rid of the garbled terminals at all resolutions. Terminals are back to normal when gfxpayload is not set in the 00_headers file. When gfxpayload is set to keep I just get a flashing cursor in the tty windows. This occurs at GRUB_GFXMODE= 1280x800x24, GRUB_GFXMODE= 1280x800, GRUB_GFXMODE= 1024x768 and GRUB_GFXMODE= 800x600. So I guess the bug is still there as I cannot access the tty other than at the lowest resolution.