I have a bathroom sink that's leaking from the overflow drain. It's old? Installed 20 yrs ago by the plumber from hell. The overflow is NOT built-in. It somehow goes from the overflow opening in the sink to a opening on the sink drain via a vinyl plastic tube. It is attached at the drain by zip ties. The attachment at the overflow is an issue since it became disengaged. I cannot figure out how it was done nor how to fix the problem. The drain attachment is unusual. Inside the drain it's slotted to allow overflow to drain out. 1) what's up? No plumber or plumbing supply can tell me what I have or what I can do. Can I forget the overflow, plug it and somehow disengage the drain holes? Can I remove the drain overflow and replace it with a new normal sink drain? Can anyone tell me I am not crazy and acknowledge that I have something unusual.