There's no reason why glue at the bases of the capacitors would be burned. So I think you have a red herring there. Most likely culprit is rectifiers like Nigel says. If it has a switched mode supply, try testing the resistance across the mains wires (both ways). If it is low (continue test for 30 seconds to allow caps to charge), you have a short across the mains and can rule out the rest of the sub, concentrate on the psu. Note, this test is useless if it has a linear supply - you would have to disconnect the transformer secondary and test across where it connects to.
Could you get a schematic for the sub and post it here?