wirlybird,

I recently bought a new printer (the same powerspec ultra 3d) and with the same simplify3d settings as with the old powerspec it prints fine. I am still trying to fix the old as I would like to have two functioning printers. This leads me to think it is more mechanical.

noiseboy72,

I think that you are correct. Like I said in my original post, I don't think the pulley is loose because it isn't fixed by a set screw but is just fitted on the stepper motor shaft by a D shape hole so that it can't slip.