PCIe-5 sleeving guide (page 5)

A perfect first crimp in the big slot.
After a successful first crimp in the big slot, crimp it a second time in the smaller slot (17 to 18-AWG). Close the tool very carefully. Keep the cable in perfect position while closing. The cable-tie right next to the jaws of the tool will prevent getting distorted filaments within the weave structure of the sleeve. IMPORTANT: Pre-open the tool if you feel that the closing force becomes too high / damage to the crimp terminal etc. occurs.
As mentioned before: Ideal results need practice and absolute precision. Repeat previous steps until you master it. If one of the rear wings breaks off in the crimping process, it is acceptable, because an additional stability will be provided by the upcoming melting process and you can continue with this guide.
Pull the cable-tie off of the cable, over the crimp terminal. You can re-use this cable-tie, as is, for stretching all future cables until all wires on the 12V-2×6 / 12VHPWR are sleeved.