Make sure you put your weight in your heel, rather than on the front of your foot, on the balls of your feet. In other words, don't tiptoe on the elliptical.
Ditto on pushing through your heels -- that's the best change you can make. Alternating going forward and backwards can help. Also, try loosening your shoe laces.
I found that it naturally improved over time. My nonscientific theory is that all the supporting structures in my feet got stronger with regular workouts.
I had this problem when the guy at the shoe store convinced me I wore a 9 1/2 instead of a 10. Sure the shoes felt fine walking around the store, but they didn't make it in my workouts (blisters, numb/tingling toes, heel chaffing, etc).
I had this problem in the beginning. It got so bad that I had to cut my workout short due to pain and numbness. I found it did improve as I lost more weight. I also try to make an effort to wiggle my toes and try to lift each foot off the pedals for a quick shake every minute or so. I can usually do this without interrupting my workout. Now, at a lighter weight, I don't have the numbness nearly as much. Good luck
I had this problem too. I talked to my chiro about it when I was in for a visit. His advice was to go through the full range of motion of your foot . so not just your heel or just your forefoot roll through the whole thing like you would walking or running. This was a solution for me. Hope you find something that helps.