ProMedia 2.1 (Switched w/Fuse vers) Low Volume Sub

[nonionizingemf]

I have two subwoofers that look like the same model.  So I have two questions.

1.  The subwoofer blows a fuse when powered on.  What is the common cause for this?  I am noticing ~600ohms from the speaker and that should be 6ohms.  I haven't checked anything else as I noticed the sub speaker was installed sideways and the connectors might have already been disconnected when I removed the backplate... I reconnected with a fuse and same deal... little hum and blew the fuse.  I happened to only have a 2.5A and 4A fuse also.  Looks like they're 2A stock.  What is the common cause for this? 

2.  The second subwoofer wasn't working at all, though not blowing fuses.  I found the two 1000(1K)ohm resistors pads completely off the PCB.  I resoldered those and found that one satellite speaker would not work.  I also found the headphone out was working in stereo... so I concluded must be the barrel plug and not the DIN/(PS/2) connector (I repaired another satellite set with a keyboard PS2 connector that was good since the POD DIN that looked like a PS/2 was broken off at the tips). 

So, I cut the barrel plug off, tested continuity of each wire which was found good and soldered a new 1/8" barrel plug on and both speakers work now. 

The only issue is the subwoofer volume is really low.   I have the typical burnt area on the PCB around the resistors and MOSFET's on the LF board.  I tested the MOSFET's and transistors on the LF board out of circuit and they look OK.  I tested the resistors and diodes in circuit and they tested OK.  I'm guessing the capacitors around the resistors and MOSFET's are the issue?  I don't notice leakage... though all the adhesive is not white and discolored brown with some having bubbles everywhere on the plate.  The inductor zip tie is burnt off on both subwoofers, so the system must have been really hot. 

Any thoughts for quick determination of root cause of low volume?

Anyone know what the specs are for the WIMA capacitors used also on the upgrade kits, looks like a 1uF 63V on the LF board and I'm not sure of both and on the PS board?

Any reason why not to use Nichicon MUSE capacitors rated at the next higher voltage and higher temp on the LF board if I replace them all other than cost, I was wondering if any part of the circuit needs more ESR at the lower end maybe to filter DC power so not as audio noisy?

I was also thinking about cleaning the solder mask off some of the PCB traces and soldering more solder on to dissipate heat and handle the power.  Looks like the upgrade kit adds some wire also. 

Thanks in advance for your time and consideration. 

Edited January 27, 2019 by nonionizingemf
Typo and add more detail