First, remove movement, band, and anything else such as a rotating divers bezel from case.
Fitting round mineral glass crystals: (1) Determine thickness by measuring original or the distance from the bottom of the bezel grove to the upper edge of the bezel. (2) If bezel has plastic seal remove it; if there is any glue or epoxy soak the bezel in Attack epoxy solvent or something like it to loosen it and scrape it away. (3) Measure distance across bezel. If bezel had plastic seal measure across bezel. Choose a plastic seal that is of the appropriate size, insert it into bezel, and measure the distance across bezel with seal in place. (4) Choose crystal of appropriate size. (6) If bezel has plastic seal press new crystal in using a crystal press; if glue in type apply a small amount of epoxy uniformly to bezel and insert crystal.
I use ultraviolet epoxy on all glass crystals. It works wonderfully and makes a very strong, invisible, watertight bond.
To clean dial, always use blower and a sharpened piece of pegwood or toothpick to remove dust and broken pieces of glass from surface. Then use Rodico or something like it to remove any other residue. (Rodico is like silly putty and can be purchased from most material distributors.)
It is always best to remove the hands when cleaning the dial or to straighten them.
To straighten hands, use sharpened pegwood and tweezers, hold hand steady by inserting pegwood through the hole in the hand and use tweezers to manipulate hand. You can also use a hand or balance tack to hold hand steady.