Brillion seeder not covering alfalfa seed

I'm having trouble with my Brillion seeder not covering a large amount of the alfalfa seed it's planting. This is only the second time I have used the seeder to plant alfalfa. Last year I noticed that it left more seed on the surface than what I would like.....I got a okay stand but it still bugged me that the seed on the surface dried up and there are a few thin spots. This year it seems to be much worse with over half the seed on the surface. I'm planting roundup ready alfalfa this year and with the outrageous cost of the seed I hate to see that much on the surface. I can't help but thinking the problem is the ground is too firm and not enough loose soil to cover the seed......but everything I read tells me alfalfa needs a very firm seedbed? Has anyone else had this problem......not sure what I should do?

I have mostly used my seeder to plant timothy and always have excellent stands with minimal seed on the surface......timothy seed is much smaller though than alfalfa and doesn't take as much to cover it.

Brillion seeder not covering alfalfa seed