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Usually I start with removing the TV's back cover and verifying which Fan is not spinning. That would be the #2 fan. There's a BLUE paddle switch you hold down right by the lamp. You have someone turn the TV on while you hold that switch down. To the LEFT of the lamp, you'll see an obvious fan, that's easy to view. I'm pretty sure that's FAN #1.
The #2 lamp...that's actually BEHIND the lamp itself. You can remove the lamp, look inside the lamp chamber Way back and to the right side of the chamber you'll see the fan. Use a flashlight and see if that spins or not. They usually get bound up due to heat and dust . I have pictures showing how to take that lamp chamber apart if you want them.
You see that access panel for the lamp - When you remove it, that blue switch is right there held down by the access door. . When you remove it...the TV won't start up. It's got to be held down, or the little plug unplugged from it and a small jumper wire inserted across the plug. NOW the TV will turn on and stay on. BUT...you remove the lamp to check that fan....it will stop the TV too. Either way you want to check that fan as described with the lamp out and the blue switch jumpered or held down. I will send those pictures tomorrow morning. it's 11:30 pm here.
Here's 5 pictures showing how to get that lamp fan removed. Look at all of them first, one shows that blue paddle switch highlighted, and where the fan is located behind the lamp. Also shows how to remove that air duct/director in front of the lamp. Removing the back cover first gives you better access to the work / Testing area.
And here's picture 4 and 5