Here’s what Black Diamond says about replacing slings on cams:
• With occasional use: slings should be replaced every 5-8 years
• With frequent use: slings should be replaced 2-5 years.
Re-slinging Black Diamond Camalots and C3s
So what and how should you re-sling your BD cams? Of course you can do anything you like:
• One-inch tubular webbing with a knot will work.
• Sending them to someone that knows how to sew structural climbing gear, and have them bartack a single loop of SuperTape will work.
• Having someone that knows what they’re doing bartack a double length of SuperTape or 10 mm Dynex will work.
Lots more photos and test data at the link.