Sorry to hear the zippers don’t pull easily. I had one LV piece recently that was that way. To fix I simply took a piece of waxed paper which I have around though rarely use, and rubbed the waxed paper on both sides of the zipper and then I shut the zipper and rubbed it on top of the zipper and then I opened and closed the zipper several times, repeat and now the zipper works beautifully. Nothing comes off of the paper but it does help the zipper work smoothly. I’ve used pencil lead on coat zippers, But only when the coat was dark, I wouldn’t do that on an LV and bag. Hope this helps!