I know old thread, but..
Here in the states JASCO Denatured Alcohol is in the paint section of most of the big box hardware stores:
Ethyl alcohol {Ethanol} 30.0 -50.0 %
Methanol {Methyl alcohol} 40.0 -60.0 %
Methyl isobutyl ketone < 1.0 %
It's the ethanol that breaks up the oxides... and it works. Just don't drink it or try to use it as hand sanitizer!
I would worry about the Methyl isobutyl ketone...which is an acetone derivative...so how safe is it when coming into contact with any plastic parts in and around the cleaning path...over time, with lots of use?
I know we've covered much of this already...but I just wonder how dirty people let their tape decks get, or what quality of tape are they using, that there would be a need for stronger solvents to cut through the tape residue...? Maybe if you're reconditioning some used deck you picked up...but I find that I can run my tape deck all day long, and I never see even a spec of residue on the cotton pad when I clean it at the end of the day.
So for me, plain isopropyl 99.9% pure is still the cleaner of choice, and IMO, it's the safest one.
I think I have around a gallon of that stuff right now...I picked up a couple more quarts after the COVID-19 stuff hit, because I thought it would be hard to get...but it wasn't a problem, though I doubt the average person would know to look for alcohol at an electronics supplier.
Mind you...even if they did, the 99.9% stuff is not good for sterilization...it has to be between 60% minimum, and 91% max...which is why you never see anything higher if you get it at your local pharmacy. Apparently, you need some water in the alcohol for the disinfection to work...it acts as the catalyst.
I guess if you have 99.9% pure alcohol you could simply add the right amount of water to it...?
Of course...you don't want any water in it for tape deck cleaning...since some metals might rust, but I think that would be a concern for real old decks.