Need help fixing my Casio MT-11

[hyaki]

Hi guys,
I'm having problem with my MT-11;
The power led is on, the speaker clicked upon switching on,
but all notes are mute no sound at all even when volume knob is at max.
I have check;
1. The power is okay distributed either using 5x AA battery or 7.5 DC Adapter.
2. Volume pot is normal, speaker tested on other circuit and it is good.
3. Carbon pad on board for switches are in good condition.
4. There is no Caps leaked, trimmers are in good shape, and no rusted components.
5. The CPU HD44140 has two of its pins disabled (pin with no legs to the solder pad) //not sure if this intentional or damaged.
6. Browse trough the net for MT-11 and its CPU HD44140 but no clues about my problem.

If anyone has a working MT-11 would you confirm my finding about the point number 5 above?
Heeelp me Masters.... what do you think it's wrong with my keyboard?

Thanks

[Circuitbenders]

I take it you have tried the headphone out (if there is one) and the normal output? The first thing i'd suspect would be switching in the jacks that probably turns off the speakers. Are the speakers actually hissing when you put your ear right up to them?

If it ever worked then i doubt the legs on the HD44140 are the problem. Thats the main CPU right?