Replace the tank grommet. They are still available new.
Part call-out #4:
https://www.cubcadet.com/webapp/wcs/...0-A/0028100004
On a quick interesting note, the section headings are messed up on the online parts book for at least the 1650. The muffler duct work, and the fuel tank and connections are under the opposite headings for some reason.
