No complete printing after installing a new drum

Just bought my second drum and installed it as specified. I followed the instructions where they say that we should clean the primary corona wire inside the drum unit by gently sliding the blue tab from right to left and left to right and return it to the original position. The cartridge I am using still had over 1,500 copies left yet the printer now does not print complete pages. It shows light horizontal lines here and there and only prints a dark line or two about 1/3 down on the page and the rest is clear. Never had this problem before as the HL 2040 has been very reliable. Appears to me that the roller does not complete the rotation. Most frustrating. Can some one Please help me?