Hello Andrew.
I don't know if this is relevant but I had the lid not staying up on my Pink triangle LPT. After a look I saw it was because the 2 parts of the hinge that the lid slots into had stretched apart. This meant that the lid did not stay back far enough to 'over balance' and so stay up. My solution was to drill through the hinge and lid and fit small (M2ish) nuts and bolts to clamp it all together. It worked like new after that.
Here is a pic, you can just see the screws. Should have used black or painted them really.
Phil