Plumbing Questions? Ask a Plumbing Expert.
Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. First I’ll need some more info so I have a more complete picture of you situation.
What is the problem you want to correct?
Ok, but you haven't told me yet what the malfunction is. Is it not flushing? is it leaking from the tank into the bowl? I can't offer a solution until I know what specifically the problem is. I have a source for vintage Brigs parts. They may have what's needed.
Let me put it another way, what happens when it malfunctions?
Your plumber's opinion is not one that I agree with. Low flush toilets have been installed in houses with old plumbing since they came out 25+ years ago and there have been no significant problems related to old plumbing (in good shape). If replacing the handle and chain (flapper?) solves the problem then that's an easy fix. If you want an assessment of the condition of the parts in your tank you can post a picture here by clicking on ADD FILES next to the SEND button.