Stuart, I started with my temp set @38 as well but learned quickly that the chems don't get that warm and stay that warm once you pour them through the lift's funnel where they are also then exposed to the temp of the drum. I set my machine at 38.7 instead. Perfect e-6 results. There are other variables which may be at play here like water quality, age of chemicals, drum speed. I'm assuming you've got those under control.