I have had the same issue in the past. If you take it in to a rad shop they usually wont touch it because they say that if they try to re crimp the tabs they will break off and create a bigger problem. What I did was I removed the radiator, and used a bench vise to recrimp the tabs. I worked my way around the whole radiator adding controled pressure both down on the tabs and horizontally inwards. I haven't had a problem since and this is after three rad shops told me it was impossible to repair. It has held up for two years now without a leak and only took me an hour to fix it.