Korg Mono/Poly

Hi, can anyone help me with a faulty effects section, everything else 
works fine. The button doesn't work at all, nothing happens when I 
press it. Could it be a faulty button or something more serious, would 
it be worth having a look inside to see if it is the switch or leave 
it for a tech to go over it (finding one who knows anything about 
synths in Melbourne Australia is another problem in itself)?

thanks