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I expect these projectors are quite old now, and therefore unreliable.
You can still sell them for spare parts though - you could put them on Craigslist or a similar site for around $50 each.
As the projector units are unreliable. They are not good as units, but they are good for salvaging hardware parts from, e.g. if someone had a cracked cover they could use one from your old projector.
The bad color is likely coming from the digital image processing part of the projector, and to fix it would cost more than the price of a new projector, whilst leaving you with an old, unreliable projector for your money spent.