My X9 is showing err1 and err3 as well. It gets better with time but still gives an err3 every once in a while. It's enough to make the thing unusable.
I bought a copy of the service manual on e-bay and found the following (bad English and all):
If "Err 1", "Err 2" or "Err 3" appears in the left display at this time, the correct communications are not established between U302 (SLAVE DSP) and U303 (micro-comp.) on DSP PCB. If "Err 1", "Err 2" or "Err 3" appears in the right display, the correct communications are not established between U301 (MASTER DSP) and U303 (micro-comp.) on DSP PCB.
If the error message does not go out, the power supply voltage or DSP PCB (errors in U301, U302, U303 or others) are out of way.
I checked the schematics and the U301, U302 and U303 chips are the big flat chips all on the same board so that eliminated the easy to fix loose cable I was hoping for between them.
This left the power supply voltage.
I popped open the face of my X9 (have to remove side screws and a bunch of key caps to get to it) and was able to see the power supply while looking down into the machine.
I found a large 16V 10,000 uF capacitor with a bulging top. Not a good sign. Slapped it on my meter and saw it was only registering around 3K uF and was losing almost 30% voltage. Effectively turning it into a resistor.
Ordering a replacement capacitor tonight. Will let you know if that fixes my err1 and err3 issues.