We haven't had any issues with it falling out of alignment, but certain jobs we are choking all the way up to like 4-5 to keep the base from peaking out. We normally choke at 3 and that generally works pretty well. If we are printing on a lighter colored garment we might bring it back to 2 if the outline is bad.
Are you sure the machine is actually losing alignment? Is the machine level and stationary?