I installed a new tub drain kit with overflow. It's leaking because there's a gap between the PVC and the bottom of the tub. The gasket isn't pressed tight between the two. I can push it flush to the tub without much effort but no matter how hard I tighten the drain it won't make a seal. I tightened it to the point the crossbars broke and I can still move the whole thing around. I don't get why i can press the PVC and gasket flush to the base of the tub, but the drain won't tighten anymore. I tried less tape and less putty but nothing works. Do I need a bigger a gasket to make up the difference? Or can I just use caulk or marine glue instead of the gasket? I am trying list my house for sale and I desperately need to finish this.