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I use this page all the time to grade my primary and secondary keywords and for four years now have consistently managed to achieve A-C grades for all. Today however, I noticed I am flagging F grades for 50% of the keywords. I do make a note of the initial grades for all pages (as the majority of the keywords I grade using the tool are NOT added/tracked in MOZ 'campaigns'). To make sure I wasn't going mad I went back and graded some keywords I had achieved A-C grades for just 6 days ago. The changes are as follows: keyword 1 initially graded an A - 6 days later is still an A keyword 2 initially graded C and is now graded as an F keyword 3 initially graded C and now an F keyword 4 initially a C grade and now an F keyword 5 initially a B grade and has remained a B. Out of interest I then went and added one of the keywords that is now graded an F (but last week was a C) into the 'Add and manage Page Grades' section and graded once again - it's now grading this as a C. I then removed this keyword from my tracked keywords and graded again using the 'On-Page Grader' tool and ... it's back down to an 'F'. Please could you shed some light on what's going on? I don't want to track each keyword I grade over time but I do want the parameters for grading to remain the same if I use the 'On-Page Grader' tool - what's changed? I haven't received any alerts about any changes to the tool so if anyone could shed some light on any changes I would appreciate it.