For some time now I've been using brake cleaner spray and find it really effective at shifting old grease, wax, and general grime. Depending on the surface to be cleaned, I either spray some onto kitchen roll and apply it by hand, or spray it onto the surface (of a chassis say) and used a brush to agitate it to loosen the grime, then wipe it off. It evaporates quite quickly, leaves no residue and doesn't seem to harm plastic and polished surfaces.
It's cheap too. I get mine from an autojumble, but it's widely available from the likes of Toolstation for example, at £2.45 for a 400 ml can:
https://www.toolstation.com/brake-cl...oaAoroEALw_wcB
Might be worth a try to see how you get on with it.