Hi Dave
I have had this happen. I check all my tips prior to placing them in the sleeve and on occasion have opened a new tip and found there is no light being transmitted through the fibre. I will hold the tip up to my view box and look at the business end of it to see the circular glow of transmitted light. The tips that have damage just appear brown or black. If you place this tip on the sleeve and fire up the laser the energy is being trapped in the broken tip. Of the last 20 or so tips I have used I have had two with this problem right out of the package and out of sterilization. I imagine the sterilization process was the cause so now I check them before they go in. water and air will still come out even if the crystal tip is broken somewhere within the sheath
Always check the tips for light transmission before attaching it to the sleeve.