You need to figure out the switching action, then you can do the measurements on the pins to see what pitch you need. Afterwards Mouser, Digikey, RS Components, TME etc. will hook you up with various makes of switches that can quite easily be selected via your design requirements (type of switch, number of contacts, pitch of contacts, rated switching current,...)
We can hardly do the guessing for you. Hell we do not even know what device this sits in (PSU is a little generic), apart from the fact that this might switch 10A as well as 0.01A. Without more information: No can do.