I found (through the Mathews forum) that the Ovation performs best with a 39.5" axle to axle length. This requires quite a bit of cable and string twisting and results in your draw length being 1/2" longer than the cam is marked for. IE: I shoot a 29 1/2" 80% cam to get 29" at 80% letoff.
Since your letoff is so bad I would look at your cam timing and twist your strings/cables to get that cam timing correct. It is a simle procedure if you have a bow press available. Just because the ATA is correct at 40" does not mean that your timing is correct. Timing pictures are available on the Mathews forum or in your owner's manual.
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