As already mentioned, only a good leather cleaner and conditioner on real leather. I like the Bick products.
Do not use leather cleaner on suede or unfinished leather.
When I buy a used amp or cabinet wrapped in vinyl I always start with dish detergent, specifically Dawn. I use two cloths, one pretty wet that I’ll put a small amount of soap on and then knead it thru that rag to get it soapy and removing excess water to end up with a damp soapy cloth. I’ll take off all the knobs and handles then go over the entire amp/cab one side at a time with the soapy cloth scrubbing as needed followed by a wipe down from the clean damp cloth. I vacuum and brush grill cloth.
I start with pulling the chassis on amps and clean that first so I don’t get scratches from a dirty rag. I rinse the clean rag after each section I clean, and rinse and re-soap the other rag as needed. The cloths should not be dripping wet, just damp enough to work well without water running into jacks/sockets etc. If there is stubborn dirt/schmeg I’ll use a cleaner like Pine-sol or Mr Clean diluted per the directions on the container. Fantastic spray cleaner works well also.
Magic erasers are great for getting those areas that look like paint transfer from rubbing against something, just don’t go overboard with the scrubbing. Q-tips are great for corners and other tight spaces. I usually do all this twice unless the amp is already pretty clean.
Be especially careful not to get any liquids in tube sockets and jacks. If you do, break out the hair dryer on low heat and dry it out, then use a contact cleaner like De-Oxit to remove any residue from soaps/cleaners or any remaining liquid.
Soap and water or mild household cleaners only on anything that is screen printed. I’ve accidentally removed lettering with isopropyl alcohol, and that’s a very mild chemical solvent compared to other types. On older vintage amps I would probably pass on cleaner and just use a damp cloth and lightly wipe.
Whatever you do don’t scrub the crap out of the standard style tolex or you will scratch it, especially with a stiff brush. The rougher textured ‘bronco’ can take more scrubbing, even with a decent cleaning brush.
I avoid any ‘solvents’ like acetone, xylene, mineral spirits, or paint thinner. I’ll use naphtha only for desperate situations. The only exception with the solvents is maybe if there was actual paint on the tolex, but would go sparingly with mineral spirits/paint thinner. If it wasn’t that bad I would just leave it alone instead of risking bleached out spots. A little bit of brushed on black paint, or even a sharpie can make small blems much less noticeable on black tolex.
Once an amp is clean I’m a ‘wipe it down often’ guy, unless something has been spilled on it that’s all I need to keep them looking great. I ‘borrowed’ a couple of my wife’s makeup brushes years ago, great for getting dust off the cabinet lip under amp knobs or recessed speaker grills. I also keep everything either covered or in its case when I’m not playing them.
One thing I’m unsure of is cleaning the black speaker grill cloth, I think it’s dyed jute. I’ve contemplated using a foamy carpet cleaner and vacuum but I’m worried about leaving streaks of lighter areas so I just dry brush and vacuum.
Dom