Heavens, that doesn't make you an applicant for the dumbest quilter award... CONTINUING with the straight stitch foot - that would!
We all go through this. Had major problems with my HQ16 one day; same quilt as day before and I swore up and down that nothing had changed. Finally walked away from it because I was disgusted with, well, everything.
Next day, I went over everything before I started quilting and very quickly discovered the problem. The previous day I had to re-thread the machine, and I did it wrong. Once correctly threaded, it worked like a charm.
Thus is life.