MX922 Prints not printing middle of text lines

My MX922 was printing just fine a couple of days ago. I printed a document in Word and it printed ok, two or three hours later I printed another document and it appears every fifth line prints with some or all of the text not completely printing. Sometimes it's the whole line, mostly a portion of the line. In the affected lines generally the middle or bottom of the text is blank so I have the top half of the line or the top and bottom of the line but no middle. I ran a nozzle check and the pattern was perfect. I did a print head alignment and then printed one of the documents that I had printed before. The blank parts remained. Interestingly they are identical in both copies. If I print a different document the affected lines or located in a different area. I printed a page from Adobe Acrobat and it also printed with some of the lines partially missing but not nearly as many as the Word documents.On successive pages in the Word document the affected lines are in different areas and randomly spaced. Interestingly the affected areas are identical on all subsequent pages of the document. The same is true for the pdf file page I printed. I printed a page from Xcell that had text on it. It printed just fine. I printed a txt document from a text editor and it printed fine.I printed a Word document that I printed before this problem and the new print is just fine. I printed page from two other Word documents that I printed before the problem occurred and they printed with streaks on the new print. I'm baffled, the problem seems to be with Word and pdf documents, but not all of the documents have problems. I printed two of the documents I have problems with on my Epson printer and they print fine. So we have my MX922 not playing well with Word and Acrobat but no other document types. I printed two documents on another printer with no problems so it isn't the documents. I ran a nozzle check which was perfect. I ran a print head alignment and the problem persistes. Maybe someone can explain this, or more importantly have a solution.