Trim button as toggle mode for gyro gain

Hi,

I'm using my devo7e for mini cp, but since it doesn't have enough switches, I'm scratching my head to find alternatives for different functions/modes.

I want to make my trim button to make my gyro gain toggle between 50 or 75
I know that trim button can be used as toggle mode (i.e. -100/+100), I've sent up a virtual channel (Virt3) for it to take effect

BUT my gyro gain channel (ch7) either has no effect or simply also toggles between -100 and +100
how can I make use of trim button, virtual channel and other complex mixer to make ch7 toggles between 50 and 75?

Thanks PB for your answer!!! the trim button now work as expected

btw I changed mux of 2nd page mixer to "add", so now gyro gain (ch7) toggles between 50 and 75 now