YUCK......
According to the wiki:
http://en.wikipedia.org/wiki/NicotineNtine is hydroscopic and miscible with water......

Which means that most vinyl cleaning homebrews are capable of cleaning off N......

If you want to standardize......
My cleaning fall back is Fantastic. Good on metal, plastics etc..... with a slight amount of aromatics to hide the N smell.
Attack the amplifier with surface area in mind. So as mentioned above, take off all of the covers, ie top (which is usually 3 sided) and clean the backside. If you can remove the bottom plate (usually revealing the PCB soldered side), I use the Fantastic liberally on that too.
Now, the tricky part, I spend time with the amplifier heat sinks. Love those machined fins......

Another piece(s) consisting of large surface area (for cooling). If these run hot (ie loud), then the N aromatics will usually cook off of these and that ambiance of the smokey, small, crowded jazz club is duly simulated.
I attack these with a Q-Tip loaded with Fantastic and rub / clean till there is no more amber color on the cotton.
Hopefully, this will rid the amp of toxic N smell. Or for some realism, leave some surfaces untouched, put on J. Coltrane Live @ Village Vanguard, close your eyes and let the sound stage take over......
Of course, the outside of the unit is cleaned first......

Forgot to mention, as it's the first thing I do with vintage equipment......
Good luck.
Fred
Music is Everything....Except Predictable....WFUV Fan.