Looking for some help with the opthoma HD20.

Hey everyone. We've had the projector for about 7 years and has been great. Lately it has had some problems with the colours as after a few hours it starts blinking with purple green making it unwatchable. I can tell when it's gona go on the blink because there's a yellow patch everywhere. My mother is hosting an Oscar's party next week so it's imperative that it's in working order before that! Appreciate any words of advice!