dstjohn,
I seriously doubt the new lines will solve the problem. Also, you cannot clear the caliper passages with compressed air thru the bleed nipple hole to the brake line hole; they are connected directly together. All you'll clear is the 1/2" long hole between them. The passages and the cylinders are "dead ends".
While you have the system drained for the line replacement is the perfect time to clear the calipers. They are stupid-simple: 4 bolts and an O-ring. Then you have easy access to clean and check the passages and pistons.
See disassembled calipers here:
https://photos.app.goo.gl/vdJIe8VNu17u4Z9N2