Replacing the caps should cost you almost nothing. Try one of these places.
https://taweber.powweb.com/store/capord.htm
http://tubesandmore.com/
Also, you can sometimes find 200v power supply caps in computer power supplies or in old monitors. The value doesn't matter much in this kind of amp, anything from say 8uf-50uf will probably work. I'm sure that amp isn't hifi/doesn't have good bass, so it doesn't really matter what value you use.
Note, however: even if your filter caps were dying and your signal caps were leaking DC, you should still hear SOMETHING when you play the guitar. So there may be another problem somewhere. Take some voltage readings, check for broken connections, etc. Also, new tubes is always the first thing you try when an amp is sick. So, when you buy your caps, you should probly buy some tubes too.
Here's a trick... you say you can hear crackling and popping in the speaker. So something is getting through the power amp. Assume for the moment that the power amp is good. Take a probe on your multimeter and touch it to points in the signal chain before the power amp. You should hear a pop. If you don't, you know that something in that stage is wrong and killing the signal.
Some pics of the exposed chassis would be interesting, perhaps helpful.
These guys can answer any question you have.
http://www.el34world.com/Forum/yabb2/YaBB.pl