The other thing that’s important besides cleaning is making sure your material is FLAT. I see people complaining all the time about not getting cut-through, and the photos they post show the material just lying on the bed of the GF with nothing holding it down. None of the stuff we cut in the GF is going to be absolutely flat – NONE of it. There’s always a tiny bit of warp, and that’s all it takes to keep the precise settings from not working. Magnets and hold-down pins are your friends!
I’ve had my GF for 8 months now. I can only remember ONE instance of it not cutting through PG material that wasn’t explained by dirty lenses or non-flat materials. The problem never repeated itself, and all I can figure is that I got a sub-standard piece of PG. Considering how much of the stuff I’ve used, though, that’s a pretty good record.