Hi, I was given a cnc-ready Taig mill (year unknown, 2011-2014 most likely, acme leadscrew) a little while ago and am in the process of getting it up and running. I am currently dealing with a stuck Y-axis and would like help and opinions on troubleshooting.

After receiving the mill, first thing I did was rewire the motors quick and dirty, then plugged it into a friend's setup (she has a taig as well, though different year/model) in accordance with the drive & motor datasheets. Everything worked. Motors are wired bipolar series, drive is a geckodrive, control is a custom linuxcnc box. All of the axes drove without issue. Cool. This is where I start to make mistakes.

I noticed there was a ton of play in the Y-axis. Apparently the gib was loose. I tightened it up a bit and figured I'd test it later.

A few days later, I rewired it again with nicer cable, proper strain relief, and fresh connectors. I checked with a voltmeter. Resistance was still correct, no crossed phases, no shorts, correct current-sensing resistor in the DB-9... Looking good. I hook it up to a new linuxcnc computer (same power supply, same geckodrive, different computer & DB25 cable), get the settings in the ballpark, and run it. The X- and Z-axes sound/move just fine, but the Y-axis isn't moving. It looks like binding due to a mechanical part, but my friend insists it's probably a wiring issue that the voltmeter isn't catching.

I've tried the following:
- Reattached to previous computer with all hardware/settings same as when it worked the first time - Y-axis still binds
- Resoldered connections between cable and motor - No improvement
- Loosened gib, tightened gib, loosened it completely - No improvement

The only possible lead I have is that the Y-axis feels a little tight when I try to turn it by hand (whether gib is tight or loose), but I don't have a reference point for what it's supposed to feel like. I can turn the leadscrew by hand and the carriage moves. It feels a bit tighter than the X- and Z-axes, but I'm not sure if it's tight enough to cause this flat-out binding. When I try to jog it at low speed, the lead screw will rotate maybe a few degrees in either direction and I can see it pushing on the Y-motor mount a little bit. When I try at high speed, the carriage and lead screw won't move at all.

Anyone have experience dealing with taig mills? Where's a good starting point for diagnosis?

edit: also, the y-axis is not locked (at least not deliberately by way of the gib lock screw)