What is a good cleaning agent for components

A folded Bounty paper towel sprayed with some distilled water and 91% isopropanol. No need for anything fancy!

And for metal surfaces a perfect cleaner is neoblank -- used exceedingly spaingly, cleans the surface with no residue and no risk of marking -- this is a huge quantity (75cl) -- can be found in 50ml packs which will last you for ever
https://www.amazon.com/Neoblank-Stainless-Steel-Lubricant-Neodisher/dp/B01MYLK4EV

Never clean the face of a component. The letters (on/off, source, etc.) are usually silk screened and anything other than water will melt them off. This is why used equipment, found in audio stores, is usually dirty (they won't take a chance of damaging anything).