am i dethatching correctly?

[dlandscaping]

I have an older bluebird "lawn comber" with the bagger thing in the back. It has a robin engine on it and you pull the lever along the left side to engage the blades. The height is all messed up so how do i know how far the blades should reach. I used it on my lawn as an experiment raised it as high as i could i think and i ripped up a ton of stuff. I got dirt grass dead and green grass all up. I hit the dirt and it some places tore up the grass and thinned it out it most other places. Is this right or wrong? I was thinking of getting a newer one because i dont think this one goes high enough. How should the lawn look after a proper dethatching job?
PS this was a nice thick green lawn.

[mdb landscaping]

if it was a nice thick green grass, you shouldnt haven gotten down to dirt, so that tells me it is set wrong. even with a nice green lawn, you will get up a lot of thatch, but it shouldnt go to dirt, unless there are some mossy spots or something. i dont know what else to tell you though, either raise it up or show us a pic so we can decide if it was done right or not.