Hello Gale, < ... so In the "Realtek" Control Panel, I would suggest clicking the "Speakers" tab and turning
up the right-hand slider for "Main Volume" to as loud as it's comfortable to listen to. >
Do you mean I should set this to max. every time I wish to make a recording?
<Note that when you move the input level slider for stereo mix in "Sound", the input level slider for stereo
mix in the Realtek control panel (and the input slider in Audacity when its recording device is "stereo mix")
should all move to the same level - all three should be interlinked. >
Yes, they do. All three in sync. Good.
<When I said "Please try amplifying an Audacity recording from the radio to make sure it is recording what you intend", yes I meant record something from internet radio using Audacity. >
Thanks for confirming that.
<It's also important to note that in Windows Vista and 7, every application that produces sound has its own volume control. If you right-click over the Speaker icon by the clock > Open Volume Mixer, and then play the internet radio, you will see a volume slider for the web browser has appeared. The volume slider for the web browser must be turned up as well as the main Speakers slider. Otherwise, the web radio will not be audible and so stereo mix will only record silence even if correctly configured. In other words you cannot turn the radio down because you want to work and then record it at a good level. To do that you have to plug headphones in and then not wear the headphones.>
Oh boy! My brain is overheating again I think .....

But I do understand what you are saying here Gale.
It may be of interest to note that when I turn the volume thumbwheel on my Aspire 8943G laptop, the left and
right sliders move together in sync. , but not at the same level.
Not the slider in the middle (System Sounds) of course.
Just one more question please.
My "wave form" looks like like this:

- wave2812.PNG (125.3 KiB) Viewed 1253 times
Is that a normal "reading"?
When I was using Windows XP it was much more pronounced/dramatic.
Thanks to the support and advice of you and Steve, I can at last record BBC radio broadcasts of my choice.
To say I'm relieved is an understatement!
I'm now going to try to save the files I record in mp3 format.
This will enable me to copy the files from my laptop to my Creative MP3 player.
Peter