Here's a quick reference on Newtonian Reflector collimation:
- On the bottom of your scope, there should be 3 Philips-head screws near the edge of the back plate that hold the mirror cell to the tube frame. First Time, I'd rest the scope on a bed, remove the 2 lowest screws first, then the top / highest screw. The cell should fall backwards.
- Rest the cell on the bed, and you'll see 3 clips that hold the mirror in place. Each clip should have 2 tiny Philips-head screws. Carefully remove these, and put them in a pile / container with the other screws. Each clip should have a felt and/or thin rubber pad that presses against the mirror. You can wipe these with a paper towel if they're dirty.
- Clips removed, lift the mirror free of the cell, touching / holding ONLY the uncoated edges, and/or the uncoated back.
- IF the mirror is just dusty, place a soft rag beside the sink, and rinse the coated surface under the tap. If there's gunk stuck to the coated surface after the rinse, spray the gunked spots with Windex, 409, etc., let it sit for a couple of minutes, then rise again. 409 is great a loosening grease-type gunk without scrubbing. But, if there's still spots, use a CLEAN finger + more cleaner, and GENTLY rub the spot, then rinse. Still gunked? Take 3 Kleenex tissues -- or better yet, Lens Tissues -- rolled into a small ball, and use that with cleaner to gently scrub those spots. That should remove all but the most stubborn gunk. (Here at The Swamp, I get speckles of pine tree sap occasionally that is tough to remove!)
- After the final rinse, I stand the mirror on its edge on a soft rag or stacked paper towels, and let the water drain off. I use another clean ball of tissues to nudge straggler drops down & off. Then, I lay the mirror flat on the rag, and let it air dry.
- Once the mirror is completely dryI do my final polishing by exhaling on the coated surface; then, using another clean tissue ball, I start in the center, and very gently use small circles to move out to the edges. Little to no pressure on the tissue ball.
While the cell & such is apart, I remove dust / dirt from the insides of the tube. I check the small mirror (the secondary mirror), and if it's dusty, I use a Puffer Bulb to remove the dust. If it needs more, and your hand is small enough, you can gently rub it with another tissue ball. Most of the time, the secondary won't need to be dis-assembled to clean it.