I'm about to instal a new Toto in our upstairs bathroom and hope not to have to spring for another in our downstairs john... but... I took the tank from the upstairs bathroom which never really flushed very well anyway and replaced it on the downstairs toilet whose tank had broken... everything seemed ok except that it had a very slow leak at the water supply line and bottom threaded part of the ballcock unit that it joins up with (don't know what its called exactly... sorry )... so I tightened it a bit more, and don't know if I heard a wee crack but it certainly started leaking more...

turned off water supply, and replaced the 12" flexible supply line with a straight plastic supply line cut to the right height... still the same leak... and its definitely coming from the top end of the supply line where it meets the end of the ballcock assembly... so went to our local plumbing supply store where he told me I had a cracked nut on the top of the supply line and should buy a new 12" supply line (which BTW is far too long anyway)... so I took that home installed it and began filling up the pan below with water from the leak... each time I am only tightening by hand as both the supply line and the bottom of the ballcock assembly are plastic

am I doing something wrong here... the threaded area at the bottom of the ballcock does not seem to be damaged and I can't identify a hairline crack like has been suggested in other threads on this forum

I'd rather not have to replace 2 toilets at this time of year... but... I;ve got to have this fixed before company starts arriving next week