Bill,
I replaced the original foam with high-density, closed-cell memory foam, which is really soft and comfortable. The seat is base is made from 3/4-inch thick plywood and I was able to use the original hardware to hold the replacement base in place. The entire job only took about two hours to complete and it looks professional.
The seat is fully adjustable for height and so is the backrest, and foot-rest.
Cheers,
Gary

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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)