It really simple... Take stock secondary off...Also pull off the helix..And Remove stock spring. On the Secondary inner sheeve you will notice a hole where the spring tang will go into, take new spring and install so tang is in hole, then grab helix it also has a hole for the opposite spring tang... Put it together..... Now take the whole assembly and put it back on commander ensuring that the helix goes back on splines... Now with all three hands install the secondary and put the bolt on about 6 turns.....Put ur left hand behind the secondary and you will be able to feel that the male part of the helix is just a bit to the right of where it need to go in the sheeve... So Grab the secondary and spin it clockwise... It is turly maybe 10 deg... Use reverse....You have to put enough turn and pressure to override the spring tension... While holding it in this position then tighten the bolt up.... You will then have a understanding of what the action is... The spring just hold the helix up to the front side of sheeve to get rid of the clunk....It not a big deal at all really.....Tip on pushing secondary on is when you get it all the way in use ur left hand to hold pressure on the side of the secondary and it will put it in a bind so it won't slide off....Then you can use ur right to thread the bolt.....That is the hardest part....If you have an extra person thread the bolt it makes it easier.... When its all together you should be able to turn the secondary clockwise and take tension from spring and let tension off and feel and hear the helix and sheeve touching at the tip... Also if you put your secondary spreader in and it comes apart correct you know its rite.....