Lulzbot TAZ 6 failing prints

I have a TAZ 6 that I purchased from a friend a few months ago. It has been working great up until the last several prints. All of a sudden, half way through the print, the tool head will go “off course” and start printing in mid air, leaving a stringy mess. I contacted Lulzbot support and they said my X-Axis belt might be loose. After further inspection, it doesn’t seem to be loose at all. Does anyone else have any additional ideas or recommendations I can try? Thanks in advance for any assistance!

I had similar. Lightly lubed all guide bars with PTFE grease.