John Smith wrote:
My shower stall was leaking. I purchased a new strainer, cut a
hole in the ceiling, removed the old strainer and installed the
new one. Well, it still leaks.

After some detective works, I found that it is leaking between the
strainer and the gasket. The cross section of the system looks
like the following:

strainer - rubber sleeve gasket - 2" drain pipe

At first, I was able to see faint light coming through from
between the strainer and the gasket. No wonder it leaked. After
twisting the gasket, I stopped seeing the light but it sill leaks.

What is the trick of adjusting the gasket so it won't leak? Thanks.

Don't know how you replaced the strainer from below, they are installed from
above. It sounds like you have a leak in the shower base, or
under-tile-liner where the drain is installed. Depending on what you have
and how it is built, it could be simple or impossible without rebuilding the
shower floor.