AC-30 TBX tremolo channel and footswitch

[Bradders]

Hey guys, looking for some guidance from you Vox-pros......

I have a 2000 tbx.

When the footswitch is plugged into the amp it won't switch on the trem/vib - however when you remove it, the trem/vib is active and works....i can control from the amp panel.

is this simply a broken footswitch and if so - can you recommend a similar switch I might try to test this conclusion and make sure there'e nothing untoward in the amp itself? ( ie a latch switch a momentary switch or whatever?)

thanks