Remove the outside of the switchblade to check the internal components. Oftentimes if a switchblade isn't working properly, it's because of an obstruction inside the knife. Pay particular attention to the area under the switch. If you see anything in the way, move it carefully.
Apply a lubricant to the inside of the knife. Rust, dirt and debris are all factors that cause a switchblade knife to stop working properly. A thin coating of oil or lubricant will prevent the dust from sticking and stop rust from forming.
Locate the opening where the knife pops out of the sheath and look for any signs that something's stuck inside. You can do this while the housing is off or while it's still on. Remove anything that might prevent the knife from opening as easily or quickly as it once did.
Check the retraction buttons located on the side of the knife, directly below the blade. When you push on these buttons, you can easily slide the blade back inside the housing. If there's anything trapped beneath the buttons, it won't close.
Tighten up all the screws on the outside of the knife. One problem owners sometimes find is that their switchblade knife is wobbly or doesn't feel very strong. The best way to fix this is to ensure that the screws are all firmly attached. If even one screw isn't properly in place, the whole knife will feel wobbly.