Cleaning vintage amps

This is along the lines of the thread about cleaning the RCA jacks...I have also purchased some vintage gear and it is in need of cleaning.

One unit has tons of dust and dirt built up inside and even a little rust on the outside heat sink area.

Can some of you comment on how you clean your gear? Is there anything I shouldn't clean, or touch? Can I do damage to any parts of the amp by cleaning it?
Thaks folks.
Compressor with thin long rod will blow of most of the thick loose deposits. If one not available, try spray-can dust blower. Rusted components should be replaced, and heat sink easily sanded.
Power supply capacitors store energy and this energy remains stored even when the unit is shut off and unplugged from the wall. In solid state amps this charge can be substantial, in tube amps it can run into the hundreds of volts. If you do not know how to discharge the power supply caps I would suggest not removing the cover and probing around with anything either conductive or liquid. Electrical appliances have become so commonplace that we often forget there is the potential for catastrophic damage from them.

That said, I use a graduated series of fine artists brushes, Q-tips, pipe cleaners, canned air and pure alcohol. If your grocery store does not carry 99% alcohol ask a pharmacist it is cheap and does not contain the perfumes and other agents in rubbing alcohol. A magic marker and ordinary car wax will also be useful. Most of the electronics catalogs also carry little battery powered hand held vacuums although I cannot speak to their efficacy.
Pure alcohol (isopropyl alcohol) can remove the decals (logos) and lettering on the chassis.

Better to use Contact Cleaner which is designed for this purpose. It's available from most electrical supply stores.
let's not forget the good ole' Electrowash trichlor spray cleaning solvent. Ensure that whatever you use won't attack plastics.