Those are easy to get, the hard part is the price. There is a guy in Canada selling NOS 090 parts on ebay. I believe his ID is barrydm. He very well may be a member here. He has both the side covers and the complete recoil assembly. I bought from him and his is straight forward. I bought a recoil for $40, since then they have went as high as $100. Still not bad as they are about $120 from Stihl. I do not remember what the side covers are selling for. I can get you his email if you need it.
Bill