For a great intro on how to remove stubborn stickers on carts, see these two videos:

1. Use a plastic scraper tool to gently pry up and remove any sticker labels and security strips. Go slowly to avoid damaging the cartridge paper label.
2. For sticky residue left behind, apply heptane solvent to a cotton swab and dab it on the residue. Let it soak briefly.
3. Wipe the heptane and dissolved residue towards the plastic cart shell, not back onto the paper label area.
4. For stubborn residue, you can apply a diluted adhesive remover gel like “Goo Gone” or “Goof Off” mixed with water. Let it soak briefly before wiping off.
5. Use plastic scrapers rather than metal to avoid scratching the cart shell or label. Apply very light pressure.
6. Change cotton swabs frequently to avoid spreading residue around.
7. Check frequently that solvents are not discoloring or damaging the paper label. If so, stop using that solvent.
8. For thick security sticker residue that won't come up, you may need to carefully remove the top coating to get the solvent underneath.
9. Be patient and persistent, working slowly to remove all residue without damaging the cart label or shell plastic.
10. For the paper cart label, avoid getting excess moisture or solvents on it which can cause discoloration.

The key is using solvents judiciously, being very patient, and favoring plastic tools over metal to preserve the cart's condition. It can be a tedious process for stubborn sticker residues.