I bought a weird Russian drum machine but it sounds thin and quiet?

[fraseyboy]

So I got this thing:
 

 
It's an Estradin Pulsar drum machine, apparently from Russian 90s. 
 
Anyway it seems to have a really quiet and thin output with no bass and I'm not sure what's going on. I've tried running alligator clips to the outputs on the board to see if it's the jack but it still has the same problem. Here's an audio sample:
 
https://drive.google.com/file/d/0B89eWWx_TpCBMFdxbEtDRkptQlE/view?usp=sharing
 
Even if you boost the volume it still doesn't sound right and there's some clicking in the background.
 
And here's a photo of the (weird looking) internals:
 

 
 
Anyone have any ideas?

 

[Garuspik]

Check capacitors.

 

[fraseyboy]

Cool, okay. I've never dealt with this level of electronics before. Are there any visual signs I should be looking for that capacitors are bad, or do I need to test them somehow?

 

[DutchGFX]

Look for cracks or goo on the outside of the caps

 

[arteom]

if the capacitor is swelling, or bulging, it's bad. Usually would be the top, for board mount capacitors.