I'm having problems determining the source of a noise in my transfer case, BW 1356 electric shift. The case was overhauled (new seals/ bearings) three weeks ago. The noise was present prior to the overhaul. The case is back at the shop. Everything appears to be normal inside except the two plates that come together when switched into 4 wheel drive. The plates have some moderate scratches and scoring. Is this normal? Could the magnet that holds these plates in place go bad causing my noise? What does it sound like when the oiler goes bad?