They are all wrong. I don't care if Spock himself is in your "audiophile club" - it is not a good idea to put contact cleaner on tube pins. Use pure solvent.

I am a member of an audio club in my area of the country - I have never encountered a larger congregation of well-degreed whackos in my life.

Just being "an engineer" does not mean that person knows anything about the specifics of audio engineering any more than me being an audio engineer means I know anything about nuclear energy.

I have decades-long experience with using Caig R-2 Deoxit cleaner, and to be truthful, I have found many instances where it did NOT do the job. There is however a contact cleaner called Stabilant 22 which I have found to be excellent on audio connections (still don't use it on tube pins). It is used heavily in mission-critical applications such as in the military, defense, and ride control applications on things such as roller coasters where an intermittent connection can mean _death_. I think it is also listed in Stereophile's recommended components listing (not that I agree with much of what they say, but in this instance, they are right).