ORIGINAL: CDignition
Plastic gears will have a odd screw...a 2.6 MM screw is likley a plastic screw, not a machine screw..the Hitec digitals use the 2.5 x 8 mm screws...some hobby shops have them too...
Check my link in the first reply, the 2.6 is a alloy screw for metal gear hitec servos. Do a search for this or ask Mike over at the hitec board and you will see. A 2.5 will not work.