I have no plumbing experience, so this is a very basic question. I moved into a newly constructed condo six years ago. Over time, all three of my toilets -- American Standard 4010 -- have given me problems (intermittently, not constantly). Either they back up and have to be plunged or they seem to flush reluctantly. I'm open to researching and buying replacement toilets (or bowl only? tank only?), but I'd hate to do that if the problem turns out to be clogged or defective pipes. How do I know?