Is it a MagXact? If so read on...I purchased an EL400 earlier this year from DroPros. The same company makes those and the MagXact's. I have installed several DroPros over the years.
This one however was completely wigging out. Not only were the numbers flickering but it started losing position, it even ran backwards even though I was still moving the table in the same direction. I was on the phone with them for quite a while trouble shooting. Yeah all the hocus pocus bad power, poor install nonsense excuses. They decided to send me a new power supply board thinking the power supply was bad and undervoltage. An hour later I had fixed it myself.
I noticed when I installed this one the serial ports are big time SLOPPY loose. I grew up in the ear of serial/parallel ports. They are supposed to be tight on the pins. Back then you didn't even need to screw them on. This felt like the pins weren't even there. I had already tightened them with the thumb screws pretty good but for X even that wasn't enough to get contact with the pins. I had to crank it in with a screw driver.
SO if your unit is wigging out like this, my money is on the sloppy port/cable fit. It could be yours are just a bit sloppier and you can't get it tight enough to make contact reliably.
Hope you get it sorted.
