i had the same problem with a front-load machine. Feet seemed to be even, but the machine pivots clockwise about left front foot causing it to screw in (and shorten), which then worsens as it goes. My fix was to lengthen that foot more so that it seems to bear more load than the other three feet. I don’t consider it a permanent fix because that leg still manages to eventually get shorter anyway, but takes much longer.
I guess my next move is to drill a hole in a circular piece of wood giving a donut-like shape, and use that as a spacer to stop that foot from shortening under vibration.