The most common problems reported are that the pipe has stopped working or is leaking.
This is most common with the K1000 plus where users say the battery is dead. It almost never is the battery (they last 6-9 months), 90% of the time it is the coil. Change the coil. Screw it in tightly. Change the coil often. When the inside is black, change the coil. Only use coils from this site.
Leaking. The tank for the Westminster and the Kamry are sealed tanks, assuming they are not cracked, the can only leak if they are overfilled or the coil has gone. Again change the coil. Only use coils from this site.
If the Westminster stops working. Insert a charged battery. Close the brass holder. You should get a single red LED flash. If you do the bowl if fine and you need a new coil and or tank. If it does not flash you need a new bowl.
So the message is change your coil regularly. Screw it in tightly. Only buy coils from this site.
These are simple devices. A battery produces an electric current in a coil which heats the liquid which makes a vapour. These coils have fine filaments which burn out and need replacing. Like old style light bulbs.