removing bad smell

[orange]

I've got a couple of A2000s that were stored god-knows-where, and that smell badly, especially when fan starts.
What would be the best way to get rid of that smell?

[orange]

Its hard to tell what sort of smell it is. Its strong, maybe like something burning, or rottening, I relly don't know. But its there when A2000 is turned off for indefinite time.
Reminds me a bit of cellar.
I'll clean the dust with vacuum cleaner, and the rest with magic wand slightly dampen in water (is that OK?).

We really need some reliable way of cleaning (the whole) PCB or motherboard, cause Amigas are getting very old..

[orange]

I used vacuum-cleaner with brush, canned air and a bit of isopropyl mixed with demineralised (distilled) water. Its better now, tolerable.
PSU seems to be the source of smell, though everything else has some of it, too. I'd change the fan with new one (noiseless and dirtless), but it doesnt have screws. Its fastened with some metal thingy, you know..
How about puting the whole PSU in hot water with detergent?

I'd like to get some of those filters, anyway, just to be sure. But where can they be found?