I have the original (heavy, pre 2007) TL18. I had an issue with it, which was caused during transportation. After some days of investigation, I found the source of the problem and have corrected it. It worked fine in "Speed" regulated mode, but wouldn't work in "Stitch" regulated mode. One of the wires in the control box broke off and I had to resolder it back in place.
I've removed my Qbot from my Pfaff 9" GrandQuilter setup and will be adding it to my TL18 setup tonight. Then I'll be ready for some test quilting on the TL18.