Before joining this super-helpful Forum, I had emailed Humax Customer Support. They have just replied,
"To reset your PVR-9300T please follow the below instructions. Please note that performing this reset will clear your recording schedule and any system settings that you have changed.
Performing a reset can resolve issues with picture/sound issues, recording issues and also missing channels.
• Press Menu
• Select Installation
• Enter your password (default is 0000)
• Select Default Setting
• Select Yes and enter your password once more
The unit will switch off for a brief period and once it reboots it will start an automatic scan to install your channels.
Follow the below as well, please.
• Remove the used/old batteries on the Humax remote
• Press the ON/OFF button multiple times, this is to discharge any electricity inside the remote
• Insert a fresh pair of batteries in the remote
Further troubleshooting steps to continue if the above steps wont fix it.
You can reset frequencies on the remote control.
To do this,
• Turn off any other Humax at the mains(except the one you want to connect the remote to)
• On your remote, press and hold "0" and "OK" for roughly 8 -10 seconds
• You will get a message on screen asking to press a number between 1 - 6
• Press a number such as 3. The message will say remote now set to number 3 and disappear.
• If the message says ''remote code change failed'' please retry the above instructions, starting from number 1 to number 6, try the numbers one-by-one."
I should imagine you have already followed all these instructions but I thought I'd share it anyway.