You might want to also look at the pump. First, I would take it apart and replace all the O-rings using the MSR Annual Maintenance Kit ($9.95). This is always a good exercise and will help you learn more about your stove. If you have questions, the MSR website can help.

The best thing would be replacing your current pump with a new Standard Pump ($34.95) released a couple of years ago. This will significantly improve the performance, even if your FireFly was doing ok already.

If all else fails, I would second TomD's suggestion of calling MSR directly. They will know what to do. I've personally seen the parts department and if your stove is in need of parts that have failed, they'll have them.