From searching I think I'm developing a polarizer problem with my AE500. After a while (maybe 1/2 hour or so), I get a blue spot about the size of a tennis ball (just off centre on our 100" screen). The proj has about 2400 hrs of low lamp life and I just put in a new bulb about 250 hours ago. The blue spot seems to have started soon after the new bulb.

Is there any way to repair this (that's less than the cost of a new projector)? I'm actually quite happy with the 720p picture (using a recently purchased HD-A2) and I'm not really ready to upgrade to 1080p projectors. Buying another 720p projector (less money) just seems plain silly right now.

It seems to me more prevalent on darker scenes, on a pure white shot it's not even there. I've adjusted out a little blue -1 on the b birghtness that sort of thing, but the spot is still there and where it is (just a little up and to the left of centre) makes it extremely distracting.

Anyone got any suggestions on how to fix the blue spot problem?
TIA

Sure it's not a dust blob? Sounds like you aquired a "hitchhiker" while changing out the bulb. Just a guess.

I don't think it a polarizer.
Try this, go to a blank (black screen) and adjust your focus ring and see what changes, if any, happen to the spot. If it changes size, focus, it not a polarizer.
Be warned, don't be surprised if you see several other round tennis ball sized different color spots when you do this.

I tried a couple of things:
- focus in and out while the spot was there and it changed focus a little
- tried to see if it would be there on either of the R, G or B colours in the service menu and it wouldn't show up.
- tried the "paper test" on the R G & B and there were very few dust spots that way eiter and none in the same position

I guess my next step is to go get some compressed air and try to blow/suck it clean.

If it's not a dust blob, what else could it be?

It could be the LCD panel itself, but I doubt it.
Try the compressed air, give it several tries before giving up, sometimes grim can build up on the panels, that make them kind of sticky.