PIXMA TR8620a Inconsistent Printing

[mrchandler13]

My TR8620a started doing the following (shown in the attached photo) out of nowhere.  

I've tried the following already...  

1. Resetting it  
2. replacing all ink cartridges  
3. running every built-in maintenance process many times.  

  Any ideas?

[jrhoffman75]

Encoder strip may need to be cleaned. See the typical process:

Canon Knowledge Base - Cleaning the Encoder Film - TR4720