Best product for silver contact pressure switches ...

What's the best product for silver contact pressure switches that are not accessible after treatment?
....

If the surfaces are plated and clean to the naked eye, use DeoxIT® GOLD.
If the surfaces are are plated, but NOT clean, precede with DeoxIT® contact cleaner, and finish with DeoxIT® GOLD.
If the surfaces are not plated, use DeoxIT® contact cleaner.

For contact surfaces that are difficult to access, a precision spray or needle dispenser might be the best option. To prevent over-application, we recommend using a 5% spray. Apply one short burst, then wait a few minutes, then apply one more quick burst. The products are extremely concentrated, therefore, only small amounts are necessary.

If a 100% solution is desired, for extra lubrication, or if an aerosol is not desired, apply only a small amount to the switch. Operate the switch to distribute the fluid and displace the contamination.

Remember to turn off equipment, and disconnect from power source PRIOR to treating contact surfaces.

NOTE:
DeoxIT® GOLD (formerly ProGold)
DeoxIT® SHIELD (formerly PreservIT)
DeoxIT® FaderLube (formerly CaiLube MCL)
DeoxIT® Grease Type M260 & L260 Paste (formerly CaiLube Grease).