Could be a few things. Gumball machine isn't triggering it, new switch may be bad. Or from the switch to the CPU you have a bad connection or broken wire.

You could check your switch matrix in your manual and see what row and column your switch is on then check other switches on the same row and column for breaks.

LTG

I had the same issue on my TZ and even though both wires were intact to the switch, one of them didn't feel right at the solder joint. Looking closer, one wire was only connected with a few strands. I re-soldered and the msg went away.

I had that issue on my TZ and it was the alignment of the microswitch. Its kind of a pain but you could make sure the switch is working in test and if it is then keep playing with the alignment of the switch blade until the gumball mech activates it everytime. That is what worked for me. Hope that helps.