I've watched tonnes of videos and feel like I've got a good technique now, and I'm doing 3 passes, but I'm still leaving behind quite a bit of stubble, which I wasn't doing with the cartridge. I suspect I was using a fair bit of pressure with the cartridge, and I'm using non on the EJ. Could this be the reason? Or is this a hardware issue? I've tried quite a big selection of blades ranging from feather to derby in terms of sharpness and found the same with all of them.