Is poor belt alignment causing my quality issues (MK3)?  

Is poor belt alignment causing my quality issues (MK3)?

I'll preface this by saying that I know there are updated parts for the x and y axis belt assemblies that help with belt alignment and tensioning, but I'd like to get my print quality as good as possible without them so when I print the replacement parts I don't need to worry about poor quality introducing new issues. I assume that there are people with the older parts who have been able to get their print quality to an acceptable level so I am curious what (if anything) I can do without the parts.

I'll start with the Y axis. I have a similar problem that others have had where the belt is rubbing on the left (motor side) of the geared pully. I have the pully as far back as possble without touching the motor. The belt rubs on the opposite side of the idler pulley (opposote of motor side). I've checked that the belt is full inserted into the belt holder attached to the plate. It almost seems if I could twist the belt holder very slightly clockwise it would resolve the issue. I know there are versions of the motor mount that move it to the left, but I'm not sure that will fix the problem on the idler side (and seems like it would make it worse).

Entire Album: https://imgur.com/a/I3FfW

Motor pulley:

Idler pulley:

On the X-axis the belt is centered on the geared motor pulley pretty well (though you can see it move back and forth slightly on direction changes). It rubs on the front side (away from the PSU) of the idler pulley. I verified that the belt was pushed entirely into the holder before I put on the back of the extruder assembly.

Video that shows the twist and toothed gear placement (filmed upside down to better align the phone on my camera)

Idler pulley:

On to the quality issues. There are two main ones. Ghosting and rough layer lines. The type of issues I am seeing are usually diagnosed as belt tension issues, but my tension is in the recommended range. X is 249 and Y is 263. ( https://imgur.com/TWyQATw )

I printed an XYZ calibration cube from Thingiverse ( https://www.thingiverse.com/thing:214260 ) using the default Prusa PLA Slic3r settings in Slic3r Prusa Edition. That cube is on the left in the images below. After doing some reading I adjusted the slicer settings to slow down External Perimeters to 25 mm/s. This led to a big improvement on the ghosting (though it is still present) and a marginal improvement on the rough layer lines. The cube with slower external perimeters is on the right.

X (Left is default, Right is External Perimeters at 25):

Y (Left is default, Right is External Perimeters at 25):

Rough Layer Lines (Left is default, Right is External Perimeters at 25):

Do you think the issues I am seeing are related to the belt alignment or something else? I don't have ton of experience tuning print quality. Our first printer was a DaVinci Mini and there aren't a whole lot of settings exposed to tweak on that one.

Thanks!