Hi Alan,
let me try a new approach to explaining things over the internet… VIDEO! 
I recorded two short videos to show you the way how to use the fader…
The first video shows how to use the fader connected to the mixer block:
The second video shows how to connect the fader directly to the VST (without using the mixer block):
The sequence at the end of the video should just indicate that you an “learn” this fader-widget to en external MIDI-source, such as a hardware-controller or a software like OnSong. (I waited for the bubble help to appear but it didn’t pop up)
Which one you prefer is up to you. 
Good luck with it.
Hi Erik. That’s just great. It’s so much easier when someone teaches you something. I am a teacher myself and you have taught me well. I found that the volume control of the mixer fader worked well for me. I may try direct control of the VST at some other stage.
Just a quick question. When I change from picking to strumming, midi learn just registers Ctrl 3, Ch 1 each time and sometimes when I change from verse to chorus, nothing changes. Should I be midi learning for each verse (picking) and chorus (strumming). Or should it be showing “Note on” and “ Note of” ?
Hi Alan. I’m not sure what you are trying to tell me… sorry.
You say you are “changing from picking to strumming”
…by doing exactly what? (remotely controlled by OnSong or manually by pressing the button, or…)
Where does the CC3 come from, that the MIDI learn registers? Is it sent by OnSong?
When we speak of “learning from MIDI”, it means it has to be done just once.
You tell the button to listen to CC3. Just once.
And every time, when there is a CC3 flying in on MIDI ch1, the button should “hear” it and change its state.
So when you want the button to switch (once it is learned to CC3), you just have to send a CC3 from OnSong.
Maybe it has to be a CC3 / value 127 for switching “ON” (=picking) and a CC3 / value 0 switching “OFF” (=strumming).
That’s something that you could try, because i’m not sure how this CC message is exactly handled.
BTW: How do you learn the button with OnSong? You should switch on the “learn mode” of that button in GP and then send a CC message from OnSong (there should exist some kind of a “Testing Command” as far as can remember the short glimpse to the manual).
After that, the button’s MIDI-frame should read something like “<name of your MIDI-in device> : Controller 3, Channel 1”
and the button should react to every CC3 you send from your OnSong (or from somewhere else on Ch1).
And i don’t know at all what you meant by “Or should it be showing “Note on” and “ Note of” ?”
Have a look at this:
http://onsongapp.com/docs/interface/menubar/utilities-menu/editors/midi/editor/control/
Just choose a CC that is not in use and send this, when “learning” in GP is active, by using “Test command” at the bottom of the list.
You also could activate the MIDI-monitor window in GP then you can see what MIDI messages are coming in.
There should always be a “pair” of messages, one with val=127 followed by one with val=0
Hi Erik. Thanks for sticking with me. Sorry I wasn’t very clear. Sometimes when I call up a song, the mode switch is supposed to be on, but it’s off. How do I make sure that when the song is loaded, the mode switch is on?
Ah ok… i see. Well, that’s not a difficult thing to do - it’s an ideal job for variations.
These store the states of the widgets that a rackspaces contains and may have their own program-change-numbers to activate them.
You may even create a new rackspace (duplicate) which would implement even more options - it’s almost the same procedure.
Watch this video about variations (i really like this video stuff):
Your videos are good Erik. Gosh I have learnt so much in the last week my head is buzzing. While watching your latest video, I spotted at the bottom, “recall setting on load” and “recall on activate” with a save button in between. If I tick these and click save, does that do the same job (ie set the mode button) as making a variation?
Hi Alan,
to be honest, i don’t really know… i suppose it is a redundant setting, as long as it is done within a variation - i just wanted to be sure.
I guess, a variation would store the widgets conditions anyway (no matter wether those two options are ticked or not).
Those options may be important when you need a rackspace to load with some widgets set to a specific state.
What keeps you from just trying those things? 
But maybe @David can give us more details…?
Hi Erik and Alan,
“recall setting on load” and “recall on activate” restore the level of the widget with the value you saved.
For example you have a widget for controlling a leslie speed and you always want the slow speed when the rackspace is loaded or activated,
then you should use this option.
So when you set the speed to fast, the widget is for example set to 100 and you save the gig, next time when the rackspace is activated and you
save that options with value = 0, then the speed will be again slow.
Hope this helps.
Thanks Pianopaul. That’s an easy fix.
Thanks for the explanation.
Yes, I wondered about this too. Thanks, @pianopaul !
