Hi mr homer :)
All Ive got to go on is the reviews and info on the NET. They suggest your machine needs careful use to get good results and can be pretty intolerant if everything isnt just right. They also suggest that the EM0480 is a tad variable and what might be a "25" setting on yours might well be an "18" on someone elses so the numbers may not help.
User reviews on the Elektra seem to suggest a coarser grind and lighter tamp but the machines specs do talk about 8 BAR of pressure through the spring / lever so Id be starting with only slightly coarser and only slightly less tamp. The more critical trick with your machine, it would seem, is more with managing the temperature of the shot...
It might also be the amount of coffee your loading into the basket?