Downrigger auto stop question

[aglet]

Hi all, I bought a pair of older used Walker Tournament electric downriggers. They work, but they don't have the auto shut-off beads on the cables. It looks like they do have the A.S. sensor. How important are these? It looks like I could find some Big Jon crimp on ones for about $5 a magnet, a tackle shop told me you need about 4 per cable (not sure why), so I'd need 8 of them. I fish on Higgins, in about 90 ft, right on the bottom. I seem to remember I had to adjust depth frequently. Thanks for any suggestions.