Help diagnose Sonic Gear 2.1 woofer no bass

[Mikey5791]

Yesterday when i switched on my pc to play some mp3 on this speaker, i noticed the music is coming from two side speakers but the bass(woofer) speaker no sound. Normally the bass will "pop" pump out some vibration. I fed dc3v to woofer speaker red and black wire at sp near cap c23, it had some speaker crackling sound. Fyi, the woofer speaker positive side is traced to 4th leg of Tda2030 audio power amp at the bottom middle of img095833 while negative side is traced to yellow 104 cap at c27.
I opened up the inside and checked pcb(img 095833) on ac input got 12.6v at left side big cap(near J2) but no ac detected from the rightside big cap. They are both 3300uf 25v electrolytic cap. Using my cap meter, the leftside cap measured 3330uf while the rightside cap measured 2780uf.
Using my dmm, i do voltage check at 8 pin amp 4558 (those 2 pcs on heatsink) by positive red probe on pin 8 and negative black probe on pin 4. Got 18.7vdc on both amp.
Another voltage check on tda2030, positive red to pin 5 and black negative to pin3 on all 3 pieces shown 16.3vdc. is this good?
I did 200ohm resistance test on those tda2030 by pin4 output to pin3 ground, the tda2030 near subwoofer speaker line showed 5.4(is this low?). The other two tda2030 on heatsink showed high resistance(1) and i can feel the heat sink warm to touch during power on voltage test.
Appreciate very much for anyone kind comment and suggestion on making the bass to come back again. Thank you in advance.

[Mikey5791]

Also checked the control board where the volume, treble and bass pot are located. During main power on, i use my finger to touch lightly on the vr3 bass white wire and able to hear hum from the bass speaker. Tracing back the white wire of vr3 bass pot is connected to pin 1 of tda2030 near c23. This is the woofer ic. Using dc resistance scale on my dmm, i put positive probe on pin 1 tda2030 (input pin) and negative probe on centre tap of transformer black wire, then turning the bass knob to minimum anti clockwise. The resistance reading is zero. Then i slowly turn the bass knob clockwise to max bass, the dc resistance goes up to 48k ohm. Looks like the woofer ic input pin is working.
Anyone out there can help to guide me on what to check and to do next?
I am really out of clue now.