A little light oil (cycle or similar) in the latches on the front hood rail and in the location slot and rollers on top of the screen should sort it. Whilst you are at it drop the roof half way and put a drop on all the hinges and pivots of the roof mechanism, drop the roof fully and likewise on the big bottom hinges. I do mine once a year and the roof always flies up and down
Don't use WD40 unless something is seized solid as that actually dries lubricant out, and take care not to overdo things and be ready with a rag or you can get drops on your interior.