The top rack was raised or lowered depending on whether the little metal tag faced forward to to the rear. The little tab in the center of the upper rack read:
Roll-R-Rack
This end to front for tall glasses
Reverse the rack for large plates
There were steps formed in the wires that formed the front and rear ends of the rack that were offset at different places. Turned one way they sat in the frame higher for taller plates and if the rack was reversed, it sat in the frame lower for taller glasses. I showed this to some friends about their HP in 1968 after they had been using it for 13 years.
Roll-R-Rack
This end to front for tall glasses
Reverse the rack for large plates
There were steps formed in the wires that formed the front and rear ends of the rack that were offset at different places. Turned one way they sat in the frame higher for taller plates and if the rack was reversed, it sat in the frame lower for taller glasses. I showed this to some friends about their HP in 1968 after they had been using it for 13 years.