Have you tried resetting it, by unplugging the power for a couple of minutes and plugging it back in?
You can try calling DTG/SACO, who are connected with Perpetual Tech, which is the same people who made Audio Alchemy, and see if they can help. I'm not sure they're still doing business, but the last number I have for them is 805-641-7875.
Ultimately, Elizabeth may be right. The piece was a great piece in its day, but, for the price of repair, you might be able to pick up something newer on audiogon that does a better job. Technology moves on. If you liked the AA, you might look into the Perpetual Tech. I had the P1A, P3A, Monolithic power supply, all with Modwright upgrades, and it worked terrifically well. (I later upgraded.) They are a lot more than the AA, though, if repairable.