I just went through this last week with the ignition on my 029 Farmboss. Some guys around here said that the ignition was warranted for life, in checking with my dealer I found that wasn't so.
I told my dealer about what I had heard via the net and he said something along the lines of "well lets just call them and find out". He whipped out his tattered phone book and called his "guy" at Stihl. It seems that the warranty was tiered type system, something along the lines of 1-3 years parts and labor, 3-5 years parts only.
I ended up buying the part off of Ebay used for $35 and all is good.