Be nice to your Stihl dealer and maybe he will order the factory manuals. Stihl does a manual for the specific model such as 026 and then will have general manuals to cover the carb and a general manual for common items on many of their machines. The manuals run about 2.50 cost to the dealer so expect about $5.00 a piece. These manuals are NOT supposed to be distributed to non-authorized Stihl service people (me and you). So if your dealer won't order them find another he might. You can also get a parts manual for your machine to see how it comes apart. E-mail Stihl customer service they might send this to you free. I have tried twice and got one for one machine but not the other. It takes probably 6-8 weeks from Stihl, so be patient if you get them to send you a parts manual. Otherwise you can order it too for about the same money. These are very good manuals, at least the ones I have for my equip.
You may have to help the dealer figure out which manuals you need, their order list is confusing and the dealers work with so many different brands of landscaping equipment that they don't know the product literature forwards and backwards.
Good luck. This is a slow process expect ordering to take about 2-4weeks depending on how often your dealer orders.