Sumproduct Function with Other Function References

Could someone help me with the SUMPRODUCT function in my excel log? The function is found in cell K2

The way this is, is raw data will be entered in Columns A through G. There can be more than 2 Saws but the catch is, since this is raw data it will not necessarily be categorized or ordered. For example, Rows 2 through 5 may have Saw 1 logged but below may alternate between Saw 1 and Saw 2. So may the blades. Saw 1 may go through blades faster than Saw 2, which might mean Saw 1 is on Blade #6 by the time Saw 2 is on Blade #2. I wanted my SUMPRODUCT function to be able to sum up the hours accumulated for a blade from both Saws. When the first saw blade is worn out, "2" will be entered under Column G for the Saw, then "3" and so forth. Please let me know if you have any questions.

Regards,
Ty