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Chapter Fifteen - Cleaning and caring for your Slide Rule 91Repairing CursorsA common problem with slide rules is that the cursor may get broken or thehairline disappears. These problems can both be fixed with some care. If thecursor has glass faces, the only workable solution for a broken lens is a new one,and spare parts do exist for many rules. If a spare part can’t be found, often anotherrule in poor condition can be scrapped to salvage the required parts. Insome cases, a larger cursor glass can be sanded to make a smaller glass. SomeK&E cursor runner bars are notorious for deteriorating and salvage parts will beneeded, because new replacement parts are near non-existent.See the chapter titled Slide Rules on the Internet for dealers who sellslide rule parts. Click hereIf the cursor hairline disappears, disassemble the cursor and clean it well.You can refill the line with a grease pencil (like those used to mark china orglass), or a soft colored pencil, or a fine tipped permanent marker like aStaedtler-Mars Lumocolor ... and then rub off any excess outside the line orwipe it clean with a soft cloth and some Windex. This can restore the hairlineto new condition. Be careful using a felt marker on plastic cursor windows, as itmay penetrate the plastic around the line and ruin the window.Plastic cursors found on most Picketts and on rules from many makers aremore susceptible to scratching than glass cursors. Surface scratching cansometimes be eliminated by hand polishing with Novus plastic polish(available in 3 grades). Novus Inc. Item PC-20 is recommended. It is availablefrom Industrial Plastics and other plastic distributors. Call 1-800-548-6872 forlocal dealers.Careful use of a buffing wheel on a bench grinder, with a bit or rouge or finepolishing compound on it, will also work wonders on scratched plastic cursorsand cases. Take care to buff lightly and slowly to prevent overheating and damagetherefrom.Cleaning Metal End BracesCleaning metal end braces must be done carefully, as many are plated, withbrass as the typical underlay material, with typically nickel top plating(sometimes with a copper flash underneath). If the cleaning or abrasion is tooaggressive, the brass will be exposed, ruining the appearance of the rule. SomeK&E models are lightly plated and easily damaged.Metal end braces can often be cleaned with a rag dampened with Windex.Gentle rubbing with a ScothBrite pad, or a toothbrush with a bit of water andabrasive cleanser like “Ajax” or “Comet”, is a generally safe method, but do notgo too far.If more cleaning power is needed, try a brush with fine brass bristles. Thesecan be found at the hardware store, about the size and appearance of atoothbrush. Add Windex if needed. The vigor with which you brush can bedetermined by the degree of polish on the surface of the end brace. If it has a