Posted for "John Schroeder" <jschroeder@perigee.net>:

 We reamed the phenolic tube very, very slightly with a file so that the
 donut slid in easily. We sanded the donut and painted a very thin coat of
 hysol on it and the inside of the tube. We waxed the drain threads and  body
and screwed it into the donut before inserting the donut into the  tube. We
used hysol wi/ a bit of flox to secure it in the tube. We put a  piece of tape
across the hole to keep the valve flush with the bottom of  the wing. After it
dried, we took the valve out, made a bit more flox and  made a fillet with a
small tool to secure the donut.
 
 One tip we got that works very well is to wrap a layer of packing tape
 around a socket that fits a particular fitting. Screw it into the mating
 fitting that  you want. Then pack flox or micro around it. When the stuff
 dries, take the socket out and you have a nice smooth well for the fitting.
 
 Hope this helps.
 
 Cheers,
 
 John