I had a Quadrafire Mt. Vernon pellet stove insert installed about 4 years ago. Every year beyond the first, I have had to replace the igniter (Part SRV 7000-462) at least once. Last year it was four times between September and April. This is a major pain and is getting expensive ($40 each). Three questions:

How long are the ignitors supposed to last?
Is there a voltage range I should verify on the leads?
How long should the ignitor remain "on" during start up? I see mine red hot during the SS-Low and SS-Med phases.