Thanks for the pic. Any reason in particular you had to pull the QCGB apart? I'm guessing my Grizzly G0709 has a similar set up as the 1440GS and G0709 are two of the few lathes out there with the "universal" gear box for easy switches between SAE and metric threads. Really nice lathe you have there by the way, 2" spindle bore, etc.
I had a bad gear in mine and had to take it apart the first time I tried to thread. I have had an ongoing issue with the 1-8 knob popping out of position as well. What issue did you have to need to take the cover off.
The issue I have had was that there was a bad gear and it wouldn't keep the leadscrew engaged. I was just trying to learn how to thread so it was very frustrating to have it kick out half way through a thread. It took quite a while to figure out being new to all of it. I was sent new parts to fix it which luckily it was an easy to get to gear. I put it all back together and the 1-8 knob has less than ideal as far as how it engages. I have worked with it but am going to see if Matt has some ideas on how to fix it. As far as accuracy, the machine is fine, but it does lack in fit and finish being Chinese.
I know everyone says this but if I had to do it over again, I would go with the 1340gt simply for being made in Taiwan. I didn't need a 14x40 but liked the idea of the cast iron base for weight as well as the foot brake. I couldn't justify the cost of the 1440GT, but could have went to the 1340GT without issue. Had I known then what I know now I would have worked other solutions for the base and foot brake.. I just mainly do gunsmithing work.