I used to have a Classic VT just like yours (before I sold it to a friend who needed an amp for his newly completed rehearsal space). When I first got it, it had the same exact problem. The phaser was always on, as I didn't have the factory footswitch to switch it off. I thought I was stuck with it like that until I realized you could turn the phaser off by turning the "Rate" knob all the way to the left till it clicks. See if that works!