Canon MX700 printer - vertical lines aren't straight

What should be straight vertical lines print as squiggly lines instead; they shift slightly from side to side every quarter inch or so as you move down the page. And on all-text pages, some lines look almost like they're in italics, and others look like they're in reverse italics. I've tried head alignment, raising and lowering the locking arm on the print head, turning the printer off and back on--nothing seems to help. Any other suggestions?