A good place to look for parts online (for U.S. customers) is Pacific Coast Parts Distributors. Click on "Consumer Electronics", "Search and Order", login as guest, choose "CASIO" from the "Manufacturer" list, and type in "qv3000ex" as "Model Number". Then you'll get a complete list of QV-3000EX parts they have in stock as well as their other digicam offertings.

To prepare yourself for the procedure, here's a few photos of what the camera looks like on the inside, courtesy of Andrew Gregory and others.

Here's the link to the forum message where DanT gives step-by-step instructions on how to open up the QV3000EX to repair the flash.

I strongly suggest reading all the posts in that thread BEFORE OPENING THE CAMERA as others have posted replies with their valuable experiences.

And here's the forum message in it's entirety:

Opening up the camera for (flash) repair

This is how I opened and repaired the flash on my Casio QV3000:

1. Remove the external screws. The case will still be attached on the top edge.
2. Using two thin rubber "grip" clothes--the type one uses for opening jars (I believe they sell them at Wal-Mart)--hold on to the two halves of the case.
3. Maintain a constant separating force, give the two halves a continuous "wiggling-twisting" separating motion.
4. Even though it might seem impossible at first, the top edge will eventually start to separate (they are only held together by two small locking tabs on the top).
5. Carefully, separate the two halves of the case, take care not to break some of the connecting wires.
6. Unplug the ribbon cable, from the LCD display, at the socket on the main board(ease out the brown color locking bar from the cable socket first). Then remove the LCD display.
7. Unplug three other ribbon cables (again, ease out the brown color locking bars from the cable sockets first) at the bottom edge of the main board.
8. Also remove the small PCB (printer circuit board) for the top control buttons on the other half of the case(you need to first unplug two small wire cables on the top edge of this PCB, but I left the large ribbon cable between this PCB and the main board connected (I couldn't get it off). This PCB still has a wire soldered to another PCB below the main board. At this point, you might want to take a picture of this and other connecting wires with another digitcam(or draw a diagram of their connections). I accidentally broke this wire off at the solder joint, fortunately I remembered where it went and solder it back later on (you might want to go ahead and remove this wire and solder it back afterwards because it does get in the way).
9. Remove the screws holding the main board to a bracket on the left side
10. Now the main board is only connected to the battery compartment and the PCB below by a long connector on the back of the main board.
11. Unplug the main board from this long connector.
12. Remove the bracket on the left side and you'll see the power PCB for the flash. This PCB has a large capacitor (about the size and shape of a AAA battery) on it. DO NOT TOUCH the terminals or the solder connections on this capacitor without discharging it first, or you'll get a shock and may even fry the other circuits.
13. To discharge this capacitor: use two long (about three feet) insulated wires(lamp-cord thickness) each connected to an alligator clip. Clip one each to the two wire terminals (you might have to remove or push up the insulation on one of the terminals) of the capacitor. Take care NOT TO SHORT these terminals or discharge the capacitor accidentally.
14. Touch the other ends of the two long wires together---make sure you do it well away from the camera, because sparks will fly. Hold on to the discharging wires by their insulation only, do not touch the exposed portion of the discharging wires. Do it several times to make sure the capacitor is completely discharged. Now you can handle the power PCB safely.
15. Remove the two screws holding the power PCB to the flash PCB.
16. There is a small connector between the power PCB and the flash PCB, and this is what is causing all the problem.
17. On my power PCB all eight solder joints on this connector had separated from the power PCB.
18. I unplugged the power PCB half of this connector from the flash PCB.
19. I repositioned the eight little legs of this connector back on to the power PCB (the clipped-corner on the connector should match the clipped-corner outline on the PCB). I find a visor type magnifier(OptiViser) to be almost essential for this and the following steps.
20. Put a very small amount of soldering flux on the eight little legs of the connector and the eight solder points on the power PCB.
21. Make sure the eight little legs of the connector and the eight solder points on the power PCB are aligned and in contact. I held them together with a plastic clothes-pin.
22. Using a fine tip soldering iron without using any additional solder, I reattached all eight little legs to their solder points by touch the tip of the soldering iron to the each leg. Make sure the leg are not inter-soldered. If no additional solder is used, this shouldn't happen.
23. Plug the power PCB back to the flash PCB with this connector.
24. Reconnect everything in the reverse order.

My Casio has been working great ever since, and I think the connector in question is much stronger now than before.

Though the repair is not difficult. You will be doing it at your own risk. Do not attempt this if you doubt you own capabilities. For people in poor health, accidental shock from the capacitor may be hazardous.

End of forum message.