How to get my Ryobi to start?

Hi I've got a Ryobi lawn trimmer that I've had for ten years and it has always been reliable up til now. Recently when I was using it, it started clonking out on me, upon inspection I noticed the fuel lines were splitting at the ends so I pulled them off cut the ends off and then re-attached them. I'm fairly certain I put them back on the correct spigots but when I started it back up it ran for 5 seconds then conked out.I checked for spark which I have but replaced the plug anyway.I can see fuel traveling along the line into the bottom of the carb, but the line coming out of the top of the carb is all air bubbles back to the primer bubble,(which I have also replaced), which doesn't seem to want to fill up with fuel as expected. I tried switching the lines around even though I'm sure I had them correct in the first place and the fuel ran through okay but then it started leaking out of the carb.So am I right in assuming the carb is blocked? And if so can anyone advise what steps I need to take to fix it.Any help would be gratefully received. Thank you.