Thanks for that Randa but the blind causing the problem for us (OH made original post) is one of the non-cassette blinds at the front, made of a similar reflective "foil" as the car windscreen ones are made of. There are no screws to tighten anywhere, and hubbie has unrolled and re-rolled the blind many times...sometimes it works once, sometimes not at all. We are actually using a car windscreen sunshield at the moment as temperatures have hit the 30s several times on the drive. The original dark orange curtains seem to absorb the heat so that's not an option.