Hello everyone, I need help

I got a tube amp jolida model 502b, when I turn on the switch, it doesn't work so I need to find the part to change the switch (I think inside is a spring and it doesn't work). I tried so many websites but I can't find the part to change the switch. Anyone who knows, please help me to find the part jolida 502b. Thank You very much and I really appreciate it

-David