Apparently the switch contacts have a special low resistance coating that can easily be wiped off by using the incorrect cleaner or lubricant or by not using any lubricant.
http://www.krohn-hite.com/htm/technotes/technical_note.htm#Technical%20Note%20#012Switch Maintenance for Models: 330, 1030, 4032, 4600, 4601, CR series, E100RC, MV series.
The decade and range switches of the Models referred to above are lubricated at the factory. It is recommended that these switches DO NOT receive any service during the first year of operation. If you feel there is a problem, consult the factory.
Note:
Over-zealous, arbitrary, or unnecessary cleaning may damage the switch contacts, which should be maintained below 10 milliohms.
Cleaning:
Do not arbitrarily clean the switches. In many instances, lubrication may be all that is required.
Relubricate After Cleaning!
Lubricating - DO NOT USE OIL!
The use of a cleaner without lubricating could shorten the life of the switches to about two months.
Contamination From Silicone Based Lubricants:
Silicone based cleaners/lubricants should not be used where electrical contacts and other electrical components are used. Silicone will react with plastics and atmospheric contamination to form insulating films and silicone carbide compounds. Over time, silicone will react with plastics, softening them, thereby breaking down the integrity of the component (switch, relay, etc.). Silicone-based lubricants may also have been used as a mold release agent or as a general cleaner for housings. Since silicone can migrate great distances, it is recommended to clean the silicone off the surfaces. DeoxIT and PreservIT will displace the silicone.
Do Not Use Pencil Erasers:
Do not use an eraser - any type of eraser - to clean contacts. Erasers are highly abrasive and will remove the precious metal plating. Further, the glue in erasers leave behind a film that is extremely difficult to remove which can later cause intermittent operation. Rubbing an eraser back and forth across the contacts can be a potential static generator.
General Information & Precautions
When using any aerosol, the unit should be de-energized (turned off) and used in well ventilated areas.
Switch Contacts cleaner. DeoxIT is a fast-acting, deoxidizing solution that cleans, preserves, lubricates and improves conductivity on metal connectors and contacts.
Switch Contacts lubrication. PreservIT seals, lubricates and preserves metal surfaces for protection from oxidation and contamination. For use on clean/new surfaces or those pre-cleaned with DeoxIT. PreservIT contains no cleaners or de-oxidizers. It provides long-lasting protection for newly manufactured components or those cleaned by ultrasonics, DeoxIT or other procedures. PreservIT is recommended as a final treatment for surfaces that are in constant motion and/or subject to higher degrees of atmospheric contamination.
Spray Products Directions
DeoxIT Cleaner:
Ideal for general purpose applications. Contains petroleum naphtha as the carrier solvent. It is flammable but non-aggressive to almost all materials. Apply a short burst to metal surface and operate device to assist breaking up of oxide layers. For severely oxidized surfaces, wait a few minutes before operating. Then use lint-free applicators on accessible surfaces and wipe until surface appears clean. In inaccessible areas flush away oxides with DeoxIT D5. As a final step, spray a short burst of DeoxIT for protection. Includes precise, three-way adjustable valve for controlled dispensing with minimal waste and over-spray.
PreservIT P5 Lubricant:
Ideal for general purpose applications. Contains petroleum naphtha as the carrier solvent. It is flammable but non-aggressive to almost all materials. After cleaning metal surface, apply a short burst of PreservIT. If accessible, wipe with a lint- free applicator. If discoloration appears, the metal surface is not clean - use DeoxIT first. As a final step, spray a short burst of PreservIT for protection. PreservIT P5 includes precise, three-way adjustable valve for controlled dispensing with minimal waste and over-spray.