New tub drain leaks. Help!

Hi folks-
Just put in a new tub. The drain assembly is a Trip Lever Bath Drain from Watts (part 393466BA). It's a plastic drain assembly with plastic linkage. Oddly, I don't see it at the Watts site, though I see many similar drains there.
I can't get it to completely stop the flow of water, no matter how I adjust it. It slows to a tiny trickle down the drain, just enough to make an annoying noise. Lengthening or shortening the linkage to change the position of the plunger relative to the Tee doesn't resolve the problem.
In retrospect I'm wishing I had paid more for a better (brass) drain, but this thing is in, and it would be murder now to swap it out.
Anybody have any suggestions for further adjustments or tricks to make this thing stop trickling? I can just see it now. I'm enjoying my first soak in the new tub, and that trickle's gonna make me need to get out to pee..
:-)
Marc
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MAG wrote:

Bet there is slight warpage or mold flash on the stopper or its seat. Take the stopper out and inspect the sealing surface; maybe a light sanding with #400 paper. Or, try this test: coat the stopper with heavy grease. If that stops the drip, its not sealing perfectly.
Jim
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Jim-
Thanks for the tips. I'll give them a try when I get back from a business trip.
Here's the thing: the stopper/plunger is a plastic cylinder with two black "rubber" (not sure the actual material) gaskets, one near the top and one near the bottom. These were coated with some sort of goo in the bag when I bought it. I believe the goo was needed to keep the gaskets soft; I left it on and didn't wipe it off.
I'm presuming it is the bottom gasket that is the most critical one but it's hard to tell.
Thanks again; I'll report back this weekend!
Marc
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