Hello adamipswich
Unfortunately you can not map midi faders to controls like the gobo, colour, pan and tilt in Cuelux.
There may be a trick to do what you want but you will have to experiment with it.
If you use a playback for each of your controls on of the your fixture. You can add a single dimmer to this playback controlling the channel of one of the controls. This will allow you to control the intensity of the playback using your midi faders. This intensity will be mapped to for example your gobo.
Another options is to use a playback for each of your controls on of the your fixture. But this time you use a cuelist. And every cue in the cuelist will have on setting for the gobo. Pressing the Go+ button will then jump you to the next gobo if setup correctly.
I hoop that this information was useful to you.
Best regards,
Guido