There is a little black dooie on the top of the clip. it slides up and down. up for more tension down for less.
Re putting the clip on the line
When you squeeze the clip you get a single wire and a double wire. bury the cable the double wire side and let the single wire be the tensioner if that makes any sense.
like Spring Velocity ,I do not use a snubber. I use ganjon cord because its cheap. I make sure to set the brake on my down rigger so that I can pull out the line with the cannonball attached by hand. that way when you do hook bottom the line will spool out and you have time to reposition the boat to retrieve it.