I am in the CompHero performance and can see that pressing the Assign 1 Switch the sound goes to a shortened sound using some muting.

I can't see how or where the Assign 1 switch accomplishes this function?

Assign Switch assignments can be made like other Control Assignments from the part level 'Mod Control -> Control Assign' screen.

Or, as in that performance, they can be used as XA control at the Element level.

If you examine the part 2 elements you will see that elements 1 and 2 have XA Control set to 'A.Sw2 On' and element 3 has it set to 'A.Sw1 On'. Element 4 has it set to Normal and all 4 elements are in Group 1.

So if select part 2 and watch the element lights you will see the light for element 3 turn green when you hold Assign Switch 1 and play a note.

Troubleshooting Tip: when looking for the source of a sound sometimes it helps to solo each part, one at a time to determine which part is producing the sounds. Then you can solo each element one at a time to see which elements are sounding - although sometimes the lights will show you the elements.

My aim is to delete this assignment and replace it with as assignment where I can turn on a flanging effect, via the Assign 1 switch.

So now you need to decide which effect to use. Did you notice that all 4 elements of part 2 are routed to Ins A? And that is VCM EQ 501 which is then  routed to Ins B Amp Simulator 1.

You need to decide which effects part 2 will use and then which elements of part 2 are routed to each of those effects.

Make sure to STORE you work periodically as a USER performance with a unique name so you don't lose your work.

Thanks Andrew - I'll give it a go tonight 👍