Just because you are getting a servo alarm on your Fanuc control, doesn't necessarily mean that there is anything wrong with the amp. On a machine that old one of the first things you should check are the condition of the cabling for the motors and drives. I was having servo alarm problems on a Fanuc controlled router built in 2005, and I ended up having to replace all of the servo motor and spindle power cabling on that machine. The encoder cables were fine, but the manufacturer didn't use as good of quality cable for the power wires, and it was all shot (internal shorts and broken wires.).
