If you've had your Versatip for awhile and finding it's not heating as well as usual, you may need to replace the catalyst gauze.
The catalyst is where the heat is generated. Once the butane gas has been ignited and the catalyst has heated in the preliminary stage, unburnt butane gas continues to pass over the hot catalytic element (rather than burning off with a flame) causing it to glow red hot. Minimising contaminants can extend the lifetime of the catalyst, so use only good quality butane in your Versatip.
You may only need the catalyst gauze to repair your Versatip but unfortunately it is only available as a set of 4 parts as shown (part 22 in the parts diagram).
These parts are suitable only for the Dremel Versatip 2000.