Here's how I do my rug installations.
I completely dis-assembly the table: Rials, pockets, bedcloth, slates and frame.
then I lay out the rug, mark the center with masking tape, use a plumb laser to center under the lamp, parallel to the wall, set the frame on the rug one center it.
slates come back on and the rails are recovered.

I completely dis-assembly the table: Rials, pockets, bedcloth, slates and frame.

then I lay out the rug, mark the center with masking tape, use a plumb laser to center under the lamp, parallel to the wall, set the frame on the rug one center it.

slates come back on and the rails are recovered.
