One other thing to check is whether the tank is holding pressure. If you can get the tank out of the plane, put under water and blow into one of the lines while the other one or two are plugged and look for bubbles.

Also, ASP engines, I believe, are the same as Magnum. I would buy another Magnum XLS-46 in a heart beat. I cannot get over how much power mine has. It took a little to break in and get the low end tuned, but now is rock solid and very hot.
Good Luck,
Curtis