On the level 71 you do not need to get rid of all the chained pieces. You only need to clear the way for the pieces to reach the golden tiles and that will be enough.
Keep a close eye on the field, as it is essential that you do not miss a chance to create more power-ups! Do not rush into using them though, try to get a couple of power-ups close to each other and activate them in a single move. This will clear more space and will charge the Lightning power-up faster. When a Lightning drops on the field, try to use it on the chained pieces in the top of the field. If you clear at least one piece on each side, the pieces will fill the remaining golden tiles.