If cooling it down, (unplugging for a period) solves it briefly then it has one of multiple possibilities, resistor, capacitor type failure or shorting or something similar. warming it, or just plugged in, pre-warming is creating just enough heat to draw whatever component away from full connection. might be found if you shot electrical freeze spray , spotting each and every possible type of component. Otherwise, get ay an LED TV,, and if you can do a little work Craig's list get people who either don't know how, don't know what or don't believe $100 or so bucks will solve this problem of little white spots.. . Samsung, Toshiba and a few other brand names, > newer DLP (not as deep as older models, but still around 8" deep) which takes up much less space, DLP LED TVs are awesome , from 40-65" you can get either for free or up to $75 bucks. The 'tiny white spot syndrome' Then get a new chip as low as $75 up too $150 at e-bay and Fix that killer TV for another 5 years or more. Chip is simple to replace, and ought to be U-tube videos to guide ya.. you can get great color and video setting them in low watt mode which uses less than 40 watt bulb! Less than average computer monitor, way, way less than plasma and the other flat screen junk. (in comparison to picture quality and watt usage)
And for picture quality,, NO tiny pixels! Granted, they're a little older and, I guess they stopped making them cause everybody wants the thin guys, I bought a 60" 8 years ago, got white spot 2 years ago, albeit mine is on an average of 10 hours per day, and put the chip in.. Nobody, can match the quality of these screens yet. No pixel, film quality projection. easy fix, which makes the best used TV availed.