Cleaning the needle 

Remove the green/red silicone sleeve from the needle.
Remove the needle from the syringe using pliers. The serviceability of the dart can be prolonged by removing the needle after use. The mounting hub will remain in better condition and retain it's shape for longer.
Rinse the needle by passing warm water through the needle several times - giving free passage - so that the two injection ports (holes) are free from debris and foreign material. The needles may be sterilised using steam or other methods employing heat.