A month or so back a leaking radiator cap on my wife's car left me noticing that the radiator water seemed to have quite a bit of gunk floating on the top, and with a quiet Monday next week on my hands I was thinking of getting some radiator flush and trying to do a bit of a home job. I did some reading up, and while 99% of the internet feedback said it was a good thing to do, I did read one or two cautionary comments that the flush might also at the same time cause leak issues if there are already spots on the radiator that are weak for whatever reason. Are there any obvious things I can look out for prior to doing a flush, or should I wait until the next service option and get the mechanic to do it then?