No need for service remote, harmony one, etc
In the 'regular' service menu (mute-1-8-2-power):
Control > Hotel Option > Hotel Mode > ON
This will enable the 'PDP Options' and upgrade can be run as described in the service report without any hex codes, 3speed, harmony control, etc (just used the TV regular remote).
However, the upgrade did not solve the problem 100%, a barely-noticeable purple band still exists, but image is a LOT better.