I have one bike with tubular tires and patch/re-sew them when they get flats. Could use some help on the following:

-is there an easy way to locate the source of the leak in a punctured tubular? If the hole is big enough, I can hear where the air is escaping but in 2 cases the tires have a very small, slow leak and I can't locate the hole.

-I have one tubular where the base tape was old and became brittle and unglued from the casing. Where can I purchase new base tape and what is a good adhesive to use to re-attach the base tape to the tubular?

Thanks.