Any way to fix leaky ABS drain without ripping apart wall? (also, class action suit)

Greetings all!
About 6 years ago, my wife and I bought the shell of a an unusual house. Construction started around 1979, and then after a few years of on-again-off-again building, the house was allowed to dilapidate for about 15 years. After purchasing the house, we completed the construction job with the help of a resourceful contractor. All the interior plumbing, drywall, electrics, etc. was done around 1997.
Here is the problem: The pipe from the first floor bathroom sink basin leaks. We know this because, fortunately, the basement ceiling is not yet finished, and we can look right up at where the black ABS pipe comes down from the first floor and we see the water dripping down the pipe. Behind the bathroom sink, the pipe goes horizontally into the wall, then must turn down 90 degrees and then presumably does not turn again until we can see it above us when standing in the basement. When in the basement, we see the water leaking down the pipe, but since the pipe disappears into the framing above, we can't see the source. Therefore, I am guessing the only reasonable source of the leak is in the wall where the pipe makes its 90 degree turn downward. Does this sound reasonable so far?
What approach do I take to repair this pipe? Fortunately, there is a bedroom dresser on the opposite side of where the sink pipe goes into the wall, so I guess I can cut into the drywall and locate the faulty join. How do I fix it when I find it? Some kind of miracle epoxy, or do I have to cut and replace the pipes?
Also, although it is probably too much to hope for, is there any miracle product I can run through the pipes to seal the leak without me having to cut into the wall?
Also, one wonders why ABS pipe would leak so soon after installation. Perhaps faulty workmanship is to blame, but then I found out about this class action suit pertaining to defective ABS pipes:
http://www.abspipes.com/id.html
I don't know yet if my pipes qualify, but I intend to find out. Does anyone have any further information or experience with this class action suit?
Thanks in advance!
Chuck
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it will take a good proctoroligist or my gay son can help you.
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It is not uncommon for some drain pipes to get fitted together but forgotten to get glued. That would be my guess. I bad glue joint or a joint just didn't get glued. Possibly a nail or screw also, going through the drain line, that finally rotted out.
As there is no pressure in a drain line you could MAYBE just swab glue around the joint when you locate it. But if it were my house, if you have to open the wall anyway, it is not that much work to cut out some pipe and put in a new piece and a couple of fittings.

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Sounds like a leaky joint between pieces of pipe. This could be at any point above where the water is dripping of course.
The first thing I'd do is check the drain to make sure it's not the origin point of the leak. Then I'd go ahead open up the wall behind the sink where the elbow joint is located and give that a look. At that point of course you can also check the pipe itself for any issues.
If it's the elbow that's bad, it may be as simple as the piece was fitted but never glued into place. Be that case, just finish the job. If any of the pipe is bad then you'll just have to cut it out and replace it. The nice thing about these pipes is how easy it is to do the work -- they just glue right together, takes but a moment.
Repairing the drywall shouldn't be that difficult afterwards either -- you may find studs are right handy and you can just cut back to the studs then replace the piece you took out. For example, when we rebuilt the wall between the bathroom and bedroom, it just so happened that the last bit of area to cover was only a couple of feet wide so it got a partial cut that covered the plumbing to the tub. If I had to get to the plumbing, I'd cut the tape, cut an area large enough to work in, then afterward just cut a piece to fit back in and re-finish. If you're not that fortunate, you can also use some 1 by braces to hold another sheet of drywall in place then mount and finish.
James
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