General Radio 1490-G switch question

[gray5596]

After sitting for over 10 years, I tried to use my GR 1490-G inductor decade box. Discovered two of the rotary switches were flaky/intermittent. After opening it, found a light film of grease or lubricant on the switches. Some of the grease appears dried up. Does anyone know what is this grease is? (see attached picture)

This test set is well made so before attempting to clean the switches, I thought it best to ask before I do something I might regret.

[TizianoHV]

Contact cleaner or even WD-40 should do   (See Dave video https://youtu.be/fKrvtYS_6fI  min 31.30)

[Wallace Gasiewicz]

I would ask this group          https://groups.io/g/GenRad/messages
The stuff on your contacts is dried out lube, and probably could be washed off easily with IPA solvent, but since this thing is so valuable, I would ask first.

[gray5596]

Thanks for the replies! As Wallace noted, this is a fairly valuable unit and so i hate to damage the switches by cleaning them incorrectly.

[jonpaul]

STOP! avoid WD40, leaves petroleum distallates residue, not for delicate electronic contacts!

1. clean switches with 99% isopropyl alcohol

2. very slight lube of shaft, bushings, perhaps one drop mineral oil

3. Quality contact cleaner with long application tube, on switch contacts, we use Miller Stephenson, or tuner cleaner.

4. throughly exercise every switch many times just after the contact cleaner.

Afterwards allow to dry, use cotton to remove excess cleaner, test out.

We have revived decade's old Genrad resistance and capacité decades and ratio boxes this way.

Bon chance

Jon

[alm]

Something I would focus on, is to make sure to leave some sort of lubrication on the contacts. That's the problem with WD40: it's mostly a solvent with only some very light oils that will evaporate quickly. Exercising the switch contacts without any lubrication will likely result in excessive wear and tear. Jon's advice sounds good to me.

[Wallace Gasiewicz]

As already said by jonpaul,
WD 40 leaves a deposit. I don't know if should be characterized by the term grease or wax. It also attracts dust and dirt.
Watch repair, locksmiths  or even many gunsmiths will not use the stuff. If it is used as a solvent (it does a pretty good job of cleaning up old deposits) then it should be removed with IP

WD 40 was invented as a water displacing solvent.
However the WD 40 brand may appear on other products that are not the original formula.