I'm new here, and my 4 year-old Pro610HD had the same problem. Mine started acting up about three weeks ago, so I did a search on several forums, and thankfully found this thread. I fixed mine, so far no problems.
Up front, I would like to thank everyone for their contributions to this thread, and many, many thanks to Siloreed, for posting the link to his video. As soon as I saw it, I knew I was in the right place.
This post is quite long and I apologize for it's length, but I feel this information will be helpful to others.
Disclaimer: This information is provided as-is and based on my observations. I assume no responsibility for what you do to your set or, in the extreme, your health. If you feel uncomfortable going about this, then call a technician and provide him with the info from this entire thread.
I began by tapping the heat sinks on the power supply board (part # AWV1795), and got a few flickers of blue, but that was about it. I was about to put the cover back on when I decided to tap the connectors that go to it. Immediately, the screen went ballistic - it can be only described as "blue thunder"! I decided to work on it ASAP.
The following is a general procedure based on what I did to fix the board. Allow yourself an afternoon to do this, TAKE YOUR TIME. BTW, I recommend to everyone to buy/beg/borrow or steal the two service manuals that go with the x10 series HDTV's. These are ARP3051 and ARP3047, they contain info on how to get to the service menus, and parts lists and schematics as well.
Board Removal and inspection:
Turn off main power switch, wait a few minutes and UNPLUG SET. Wait several minutes to completely drain high voltages. The power supply board is large vertical board in the back on the right side, AC cord goes to it.
There is an RF coil near the connectors at upper left, be careful not to squash it with your thumb when disconnecting wire harnesses. (oops....) After removing all those screws, handle board with two hands, as it flexes quite easily. For some reason the actual PC board is very thin, in relation to the weight of the components. Try not to flex it too much, or it may cause more broken solder points. Rest the board on blocks of wood when working on it.
Use an 8x magnifying loupe (available at photographic supply houses) or glass to inspect solder joints, as you will not be able to see breaks with the naked eye or reading glasses. A cold solder joint can be described as being dull gray and/or pebbly in appearance, sometimes accompanied with a "fracture ring" around it. Found quite a few on my board. Gently wiggle the component on the other side to see if the actual joint wiggles as well. if it does, re-solder it.
As I suspected, there were broken solder joints on connector E3 (12+ supply and a GND) and the joints for and around IC204 and IC202 looked "cold" with possible ring fractures. It's amazing how little solder was used on these joints, especially the connectors. (shame on Pioneer's QC...)
This section assumes that you have had previous soldering experience, such as an electronics hobby kit, repairing something on a circuit board, etc. Again, if you are not comfortable doing this, have someone who knows how do it for you.
Work on the board in a well-lit area, such as a workshop. (a dinette set with chandelier lighting just doesn't work!) A desk lamp for additional lighting helps. Prop the board up to prevent flexing. I suggest using a magnifying headset such as an OptiVisor (available online or dedicated tool supply shops) to see what you're doing while soldering, some of these joints are quite small.
Use an AC-powered 30-40 watt soldering iron with a fine tip. Cordless units, such as a Wahl, are okay, but pressing the "on" button gets tedious after awhile, and because of the wait time for heat-up, may not be consistent. Do not use a high-wattage soldering gun, the trick is to solder the joints, not vaporize them... I used a Weller soldering station set on "4" with good results. The iron must be hot, meaning that the solder liquifies instantaneously on contact. Also used fine 60/40 rosin core solder, for PC work. Clean the tip on the iron frequently, using a wet sponge.
It's your choice if you decide to re-solder all the joints on the board, I only did the questionable ones. On the connector pins, however, I desoldered these with a vacumn pump and re-soldered them. I did ALL the connector pins just to be safe. Re-flowing solder on the other components should be sufficient, just do it quickly to prevent over-heating of the actual component. You can also use clip-on heat sinks on the component leads, if you can reach them. (the board heat sinks sometimes get in the way)
When you're finished, inspect your work - look for free-floating solder "blurbs", and make sure you didn't solder two joints together accidentally. Re-install the board, and hopefully, the flicker is gone for good.
Well, that's about it. I hope this info helps someone in the future, I know this thread helped me. Thank you again.