If you find a blue motif while hunting, try again in about two hours after a relog.
If you find nothing at all - no motifs, nothing other than green recipes - try again in about an hour after a relog.
And always check the outside containers before and after a hunt.
The nice thing about Dwemer hunting is you still find a lot of stuff to use or sell. Strange amounts of lockpicks, though... did the Dwemer not understand what a key is?