Yes to both of those. I had just assumed that it would be easier to unmod and remod later as I didn't know there was a easy way to identify what the issue was and resolve it.
well, there is two ways both is pretty easy.
1. As you say you can Play Wii Games but not Gamecube Games I think you miss DiosMios on your Wii.
Its not the only way to Play Gamecube games but it works very good .
DiosMios Formula
Install DIOSMIOS_v2.10.wad and RVL-BC-v6.wad to Play Gamecube games from USB
Install DIOSMIOSLite_v2.10.wad and RVL-BC-v6.wad to Play Gamecube games from SD-card
Install RVL-mios-v10.wad to remove DIOSMIOS and use Gamecube Disc as normal
You can find DiosMios on either ModMii or Dmlizard . i used dmlizard 2 days ago .
also, if you want to play gamcube games from usb you need to format the usb-drive correctly.
Play Wii/Gamecube games from USB-drive
A. Format your USB to FAT32 with cluster size 32kb using easeUS Partition Master. Also make the partition active and primary and first (USB1). Guide for easeUS Partition Master can be found here:
https://sites.google.com/site/completesg/prepare-sd-usb .
B. To Play Gamecube Games - Create a folder 'Games' inside the partition (USB1) and put all Gamecube ISO file(s) into your USB-drive .
C. To Play Wii Games - Download and Open WiiBackupManager . Click 'Drive 1' and select USB-drive from 'inactive' . Click 'Files' - 'Add - Files' and select your Wii ISO file(s) . Lastly Click 'Transfer - Drive 1' to put all Wii ISO file(s) into your USB-drive .
D. Remove USB-drive from Computer and plug into Wii . Also put in Gamecube controller and Gamecube Memory Card in Wii .
E. Launch USB Loader GX . Press this icon (Loader Mode) !! (
http://i.imgur.com/ioqV74i.png ) . Select Wii Games and GC Games .
.
otherwise if you was having issues and think your Wii is poorly modded...
Install modmii and run it
Goto page 2 downloads from main menu
Download sysCheck files and transfer the files to your sd card
Run sysCheck on your wii through the homebrew channel and it will save a sysCheck.cvs file on your sd card
Run modmii again
From the main menu select sysCheck updater
Enter the path of your sysCheck.cvs file or just drag the file onto the modmii screen and it will look at your file
and determine what needs updated.Follow the prompts to get the updated files and then install them on your wii.
It should give you a custom guide as well with install instructions.