Hi Bobby, Jon is correct! Don't scap that 1-18! I had a 1971 1-18 Crown with the window lid. It leaked from the same place as yours. I used a plumbers product on the area that was rusted and leaking and that repair lasted for many years. It was the clutch that ended my machines life, not the leak. It was not a "plumbers putty" that was used on mine, but some sort of a clear gel that hardened as it cured. I do not recall the name of the product, but recall that it smelled very toxic and was not to be used around an open flame. I turned the machine on it's side to make the repair. Good luck with your 1-18!
