the owners manual for the Sako 85S gives instructions for disassembly of the bolt but does not say anything about the extractor. I see no retainer pins of other method of holding the extractor to the bolt. I would like to remove it as during the last hunting season it appears to have gained some rust, possibly on the spring which would be good to have removed. any info on disassembly/assembly is appreciated.

I just machined two bolts and installed Sako extractors in them this morning. They are held in by the little plunger at the rear of the extractor; use a thin blade to push the plunger back whilst lifting up on the extractor body. With a thin tool. Be careful; the plunger and spring are easy to lose and they are smaller than a grain of rice.

Good advice and don't just hold the bolt by hand, put it in a vise.