As Bob said, you need 80mm lens. Then apropriate condenser/mixing chamber for that lens/negative size. I don't know particular enlarger, but what I said are basic rules. I had similar problem last time, I simply forgot to change mixing chamber from 50mm lens to 80 mm lens chamber... You can as Bob said use glass carrier. I don't use it. And as Bob said, if those things don't work, then check alingment. One more thing. Maybe lens is not good at edges. I had one lens which made me similar problem as you have. When relpacing it for other lens my problems are gone.