I took my oster trimmers
Unfortunately, Oster does not publish any real maintenance manuals. Basically, if you only took apart the cutting blades and the oscillator, it's not too hard. If you tried to take apart the electric motor, that's a whole different story. If it's just the blade assembly, carefully align the blade assembly with the groove pointing into the trimmer handle and hold the blades together so that they are parallel, not crooked and reinsert the screws. You will see how the blades align, based on the wear marks on the bottom blade guide. If you took apart the oscillating arm, then line up the cam pin with the round hole in the arm, then replace the screws that attach the top blade to the oscillating arm. You may have to push in the tension arm so that you can align the screws with the threaded holes on the handle first. Final step is to screw the bottom blade guide back onto the handle, again align the guide with the blades so that they are parallel and not crooked. The best way to do this is to start threading the screws, then before tightening them all the way, align the blades first. If none of this works, go to this website: http://www.osterstyle.com/CustomerService.aspx and locate an authorized Oster dealer/support center near you. You'll probably have to mail the clippers in to one of the sites.
JB