I'm in the middle of a project weaving shawls on my 40" foldable AVL dobby, and I was weaving along just fine, and then shafts started dropping, or not picking up at all. Out of a given 4 shafts that should rise, the dobby arm (I think the correct term) only picks up one or two. And it had previously been fine for several yards. I readjusted the dobby arm, and tried realigning the black computer box, but they're still dropping. Or not picking up. Any ideas?