washer. It sits directly atop the female threaded post that the hex head bolts screw into. Remove that washer too.
You may now lift the mirror out of the mirror cell and out of the lower tube section. Do not touch the surface of the mirror with your fingers; lift it carefully by its edge.
Set the mirror, aluminized face up, on a clean, soft towel. Fill a clean sink free of abrasive cleanser with room temperature water, a few drops of liquid dishwashing detergent, and, if possible, a capful of 100% isopropyl alcohol. Submerge the mirror (aluminized face up) in the water and let it soak for a few minutes (or hours if it’s a very dirty mirror). Wipe the mir- ror under water with clean cotton balls, using extremely light pressure and stroking in a straight line across the mirror. Use one ball for each wipe across the mirror. Then rinse the mir- ror under a stream of lukewarm water. Any particles on the surface can be swabbed gently with a series of cotton balls, each used just one time. Dry the mirror in a stream of air (a “blower bulb” works great), or remove any stray drops of water with the corner of a paper towel. Cover the mirror surface with a tissue, and leave the mirror in a warm area until it is com- pletely dry before reinstalling it in its cell.
When reinstalling the primary mirror, make sure to put all three washers on each retaining bolt, and in the correct order (Figure 51), before threading on the bolt. Tighten the retain- ing bolts only until the two washers between the bolt head and mirror surface are no longer loose, no tighter, to avoid pinching and consequent image distortion.
Metal washer
Plastic washer
Smaller plastic washer
Mirror retaining bolt
Figure 51. When reinstalling the primary mirror after cleaning, put the three washers on each retaining bolt in the correct order, as shown.
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