erm, I'm not sure that putting it in direct sunlight with a heavy object on top of it will actually work real well. (Is this an unknown Monty Python sketch?)
I could see putting it in sunlight to soften up the vinyl and *then* putting a heavy flat object on it. My experience is that this doesn't work too well and, sadly, Jeff's other idea is better. Unfortunately it's very hard to find replacement copies even of fairly popular older tracks. phred