Intermittent fault with twin horns sounding

I have twin horns on my 206 GTI 180, both were working till recently, I now have one working all the time and one intermittently. Would this be a faulty horn that needs replacing or a possible connection fault although if this is intermittent, I'm assuming the power is getting through! If the horns needs replacing, is there another way of removing the front grill to access the twin horns without having to work behind the grill with very limited space to be able to remove the grill clips?

Any advice would very much be appreciated

Thank you