Hal,
Sounds to me as though your Clove Currant might need either boron, zinc,
phosphorus, potassium or any combination of these. Your Crandall might need
any of these too.
'Crandall' here loses leaves when it gets hot and humid, so I suspect foliar
diseases. I doubt it is just heat stress, as 'Crandall' originated in a
hotter climate than here. There is a clump of clove currants out by my pond
that were here we bought the place. They stop blooming just before
'Crandall' gets started, so little if any cross-pollination occurs. The
early blooming clove currant has hundreds of flowers, but sets only 2-3
small fruits.
I have never pruned them. These are all planted over the past 2-3 years, and
none have gotten very large yet.