MK194N radio not picking up signal


I’ve assembled the MK194N FM radio and, although it switches on, all I hear is a soft “ssss” sound. I’ve checked that everything is the correct way round and in the correct place but it still won’t pick up signal.

Is it possible that the push buttons are each unique (ie that each button needs to go in a specific place) or does it not matter which button you put in which place?

I’ve also checked with my volt meter though and can’t find any dry joints or components that are erroneously connected together.

Does anyone have any advice? Many thanks in advance.