I need to add some down thrust to my H9 Alpha 40. Before my crash, I had it trimmed out pretty well for level flight between 1/2 and 2/3 throttle. Now, after the crash, I trim in all the down elevator I can, and it still wants to climb at 1/2 throttle. I've adjusted the clevis on the elevator up to the point where I don't think I should give it any more (I don't want it to nose down at idle speed during landings).

What I think happened was that when I reconstructed the firewall, I didn't put enough down-thrust into it, so now I need to compensate another way. Can I just put a washer or 2 behind the upper 2 engine mounts where it bolts to the firewall and call it good? Or is there a better way?