> the part that broke looks like a tiny bolt that  goes straight up into
> the drain holding the bottom up against a thin gasket. the tiny screw is =
> completely rotted away and the bottom of the drain is dangling.  the =
> plastic parts are old and fragile so i=E2=80=99m hoping I can get =
> replacements.
..........................................................
> That screw just plugs a useless drain hole, plug it =
> with silicone, and use Goop to glue the trap to the bottom of the top =
> part.
..........................................................
Well, here where it freezes, I unscrew that screw in the fall to
drain the trap, or I make sure we have had enough hot indian summer
to dry out the drain.  If there is water in the trap when it freezes
you will have a cracked trap that will leak.

If the trap is cracked then you should buy a new one.  I bet Busdepot
and GoWesty and others have it.  I win!

http://www.gowesty.com/ec_view_details.php?id=2424&category_id=128&category_parent_id=

http://www.van-cafe.com/home/van/page_244_1283/sink-trap-drain-kit.html

http://www.busdepot.com/253069183a

What I don't recommend is using the replacement flexible hose that
goes from the trap to the drain.  Instead, buy some hose at your
hardware store.  Take the false bottom of the cabinet out and make
the hose go down and work without that false bottom.  A plate
will cover the hole.  Then you have a larger cabinet space.

You can see in these pictures.  (The reinforced drain was with some
epoxy and a washer because it was cracked or loose.  The floor
and the new draintube are the key photos.

http://jones.colorado.edu/VW/SinkDrain/

 From '01 when I bought my Syncro Westy on, I replaced the flexible
drain tube a couple of times.  Since I put in reinforce hose, I have
not, and never will.  It has been there 6++ years.  I put boiling
water down it, draining pasta, for example, and it is fine.  The
flexible drain tube was not.

Richard