I would replace the tank asap, small leaks are often followed by a seam failure which would empty the tank. 75 gallon can cause a lot of damage to your house. Sorry for the bad news! Where are you located. If close I would lend a hand
So it's just what I thought bad news....I agree get a new 75. Not worth potential disaster. My schedule is pretty crazy this week, otherwise I would help out.
I can not afford to buy a new tank at this moment......sometimes I feel this hobby is not for me due to the spences.......