The most common problem on Dial-amatic problems not floating, also known as bulldozing is not having the cutterbar tiltled far enough forward,make sure that the skid shoes are not hereling out, or riding on the back of them.
Try cleaning out the packed dirt between the plates in back of the sickle and the the skid plates. Use a long stemed air hose like the one you use to clean the radiator. "Gentlely" tap the plastic on the skid plates with a sledge hamer. With the head lifted all the way up in the air blow out the packed dirt with the air as you loosen it with the sledge. Dirt can get packed in there if you back up with the head down. I do this a couple times a season.