1992 Nissan Maxima moon roof drain lines

I am aware that the moon roof on this 92' Maxima has four drain lines. I have been told by a repair shop that they are clogged and are the reason the moon roof is leaking. My question is how to clear the drain lines without inadvertently disconnecting the drain lines (which can happen by using an air pressure force I'm told) ? So, what are my options to clear drain lines? thanks' in advance for advice...........Steve