Millard

Hi everyone. I've built 4 electronic footswitches from Craig Anderton's, 'Electronic Projects for Musicians' (Project 15). I'm using them to remotely control 4 stompboxes that I have in my rack. One works fine, but the LED's on the other 3 are always on, they just get brighter when the effect is engaged. For the life of me I can't figure out what's wrong. I know the circuit is pretty outdated, but is there anyone who is familiar with it and can figure out what's going on?