Loosen up both bands with lid down, just until loose-no more because the hinge is under high tension. Line up the dome over base. Tighten lower band making sure band is as far down on the base lip as it can be while keeping dome in position. Two persons, one to hold the dome down and one to work the bands is helpful.
Then tighten the top dome band making sure it is up onto the dome lip as far as possible and level all around. Check band bolts that all is good and tight because they loosen up with heat over time.
You will have better luck by cleaning ceramic lip and installing new gasket material where it's been pulled away before you adjust bands for a good seal.
The Renaissance Man.