Good information here..Couple things to add.
1. Carry extra fuses, because your shut-off stoppers will eventually slide down and the rubber stopper and ball will come up to the pulley and you'll end up blowing a fuse.
2. Carry a pack of extra plastic shut-off stops..They sometimes fall off or break.
3. I always carry a Scotty downrigger Terminal Kit. It has a coastlock snap, 3 brass connector sleeves, 1 soft stop bumper and a stainless steel thimble. This is used to repair the end of the cable that connects to the lead ball.
4. The last thing to consider is how you clean the downrigger when finished fishing. I've noticed if I spray them down with water, then the next time I go fishing, the brakes don't seem to work like they should. After 3-4 hours of fishing and they dry out, they work just fine.
I think the manual says to rinse lightly with water....maybe I'm using too much.
I just lightly rinse and dry with a towel now.
good luck.