I think it's probably just age why your radiator is failing. The aluminum and plastic rads seem to last about fifteen to twenty years in the Hondas and Fords I service. The climate here is pretty mild, similar to Seattle.
I would think hot climates would be harder on them, due to higher underhood temperatures.
The shop manual shows radiator repair by carefully un-bending the aluminum fingers away from the plastic tanks and replacing the O-ring type seal. I considered this at one time since I had a couple bad rads, one with a broken plastic outlet and another with a leak in the aluminum part. So I could conceivably make one good one out of two bad ones.
It would have been an interesting exercise that I probably would have tried when younger, but I decided that the end result would most likely last only a few more years and take a lot of labour. And new ones are pretty cheap.
A few years ago I was able to buy a brass radiator for my Escort at "Performance Radiator", but no one seems to carry brass rads for newer cars anymore. I like them because I can fix them.
