Advice on cleaning out my stereo receiver

Crackling when you change volume is due to dirty or bad contacts on the volume potentiometer.  I get this from time to time on the sound mixing board I run at our church, and it's easily fixed using spray contact cleaner that is available just for this type of problem.  With the power off, you can spray it directly into the volume pot or slider, move it back and forth, and then power up and see if the crackling is reduced. 

If you try this once or twice and it doesn't improve, then you'll probably have to either try to find a replacment volume potentiometer, or live with the crackling.

Blowing out the dust inside the stereo can help it stay cool, but likely won't help with crackling.

Good luck!

Consider the line of products from CAIG. I've used these in broadcasting, pro audio, home audio, and hobbyist envrionments with great success. In this case, I'd suggest starting with DeoxIT Gold 100 (if you can apply it in drop format) or DeoxIT Gold GN-5 (if you need to spray to reach the area). Both of those products are safe on older plastics, and not knowing the age of your stereo or what it's made of/with, they would seem to be the safest. While they contain some lubrication, I'd suggest following them (after you've determined that the scratchiness has gone away) with their FaderLube product... it will provide additional lubrication to the moving parts for longer life and best performance. Caig products aren't necessarily cheap, but even their small size containers last quite a while and their products are long-lasting in any application. As someone who does restoration work on old audio gear, those products are my go-to. Good luck!