Slow draining sink
not sure your pop-up connector is hooked up right, anyway,, had a sink that wouldn't drain good,, pipes were clean. so far so good,, put drain cleaner down the sink overflow outlet. At some point you'd think there had to of been a backup to lead to the sink cavity getting clogged up.. Now if your sink doesn't have an overflow outlet, not sure where you proceed. Also, make sure to check pipe leading down to the trap, that is where everything will gather on the pop up linkage.
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