Rangeball--
The Diamonds are critical of stretch. They have a " sweet spot" in the cam rotation, much like most other bows with solos. If you get out of it, the bow vibrates more and becomes much more noisy at the shot, and speed drops off quickly.(which would also explain your low hits)
Optimum cam position varies on the Diamonds depending upon which cam you have on it from which year, but if it happens to be the post-feed or the one just prior to that, , then there is a machining hole directly across from the loop peg, and the limb should be coverng just about 1/2 of it for optimum position when the ATA is constant at factory spec. Let the brace height fall where it may.
This may help.
Also check to see if you are getting contact on anything with your trunock, or if the Saunders has moved. It' s hard telling without looking at the bow, but these are great places to start.
And, you don' t need a Hoyt for what you are doing, that little Diamond will treat you just fine.

[&:]
Good shooting, Pinwheel 12