New plates are available on Amazon etc for about £15, go for a PEI plate not the PC plate that comes with it. Loose screws are a problem, I’ve had it many times, a dab of Loctite threadlock helps. Don’t overtighten the screws on the Z leadscrews, tighten them then back them off by a quarter/half turn, they take up the play on the leadscrews. Screws that often come loose are the bed screws and the screws that attach to the slides on the Y axis.