Who did you buy the kit from? What type of conversion? To a resistor?(fluid)....has to be.
1. I like to leave things original and solder new wire to old (& shrink tube etc), or old wire to element/resistor if it reaches. All wire size should be bigger or equal to what you see.
2.The spring goes above some pistons to push it backwards/down.
3. Slide over exposed resistor legs and connections that may short. The big pita is usually remembering to slide it on before you connect/twist wires. Use tape just to hold it out of the way until you are ready for heat if needed, tinfoil to heat sheild shrinktube in tight spots. If you can double shrink tube it doesn't hurt (tube varies in thickness & quality.
4. Narrow center diameter down towards the piston, wide diameter up or to the cylinder- this way the wide dia. can't slip over the piston top edge and wedge. Wide dia. up, the spring hits the cylinder wall and the small dia. end is still towards the piston center.
You can solder where you choose and as needed. They make tiny little crimps if you prefered. (heck, cut the circle off a ring connector if you wanted).
One thing to note on original pellet elements is the element wire cannot be soldered to. You must encapsulate the wire in a small blob of solder. Not alway needed, but wrapping, or just a loop covered in the the solder blob, prevents pull out
Soldering, tin the wire and resitor legs first to make solder flow best.