14.4V pack. I have the same one...... You need to put the card sleeves back on from the old cells, or make new ones if damaged, to keep those cases apart. Slitting and using some tape or contact adhesive to hold the card will work. Afterwards use a spot of glue on each sleeve where they touch ( as tape will not go back in the housing) will hold them in place.
When doing those solder joints make some extra cardboard washers to cover the battery top, you will have enough space to fit it under the positive pip, so there is reinforced insulation there so a cell will not short out if it is dropped and punches through the thin sleeve. If spot welding this also works by placing before spot welding, though there you can get by with a small rectangle you glue down to the tab afterwards placed under it.