What are some common issues and maintenance tips for a mountain bike derailleur?

Common issues with a mountain bike derailleur include misalignment, bent hanger, cable tension problems, and debris buildup. To maintain your derailleur, regularly clean and lubricate it, check for any loose bolts or screws, ensure proper cable tension, and inspect for any signs of wear or damage. Regularly tuning and adjusting your derailleur can help prevent issues and keep your bike running smoothly.