Contactspray

wd-40-specialist-11-oz-electrical-contact-cleaner-spray by andromeda61, on Flickr

improves sound quality for only a couple of $$$ other brands will also work off course , great for maintaining your gear especially older gear

Details

WD-40 Specialist 11 oz. electrical contact cleaner spray is designed to safely clean sensitive electronics without damage or residue buildup. It comes in a convenient 11 oz. bottle with built-in Smart Straw – simply flip the straw up to direct a precision stream onto small areas, or flip the straw down for a wider regular spray.

Able to remove oil, dirt, condensation, and flux residue from electrical contact points, this quick-drying precision spray is great for use on circuit boards, controls, switches, electric panels, and more. It may also be used on generators and larger electric motors, and is safe for use on all plastics, rubber, and metal. WD-40 Specialist electrical contact cleaner is VOC compliant in all 50 states. Made in the USA.

Note:This product is not for use on food-contact surfaces.

It leaves a " oily " protective layer behind on switches, circuitboards , cinch connectors whatever , i did have some thoughts on start up after i left it an hour to dry but the tape machines worked perfectly i also use it in the pre and power amp .
I work as a industrial engineer ,mechanic and we use the multi spray version all the time in factories , you want metal surfaces always greasy/protected from oxidation (rust) , if those " professionals" didnt use WD 40 multi spray they obviously used something else to grease and protect .
WD 40 multispray is a good cheap alrounder to clean and lubricate machinery if taken apart or for rebuilt its not a official lubrication oil , just handy , its non food grade stuff , there also exist a high number of food grade lubricants/ greases

( BTW i also often redesign machinery to some extent , if nescessary )