Memory Check: John Deere Drill

I have an old John Deere model DR-A grain drill that I want to plant some alfalfa with.

The man that I bought it from says that he thinks it is putting down about 8 lbs per acre and he had these adjusters set at roughly the 3 1/2 to 3 3/4 mark.

The problem is that there were remains of old alfafa seed in the large tanks and I don't know exactly how he was using the drill; I suspect he was mixing the alfalfa in with another grass in the big tanks.

These are just the standard old "gear-fed" type seeders on the small grass box. I think John Deere used 'em on many of their drills.

Does anyone know about where I'd set these adjusters to get rougly 10 to 15 lbs per acre out of the little boxes? The documentation I have on the planter doesn't say a word about the smaller grass seeder and all I have to go on is my "somewhat lame" old memory of how they should "trickle out" during operation. :>(

Thanks for any help,

Allan