PVC-E gets lumpy when it gets old.  Nylon cloth that is fresh and
black is available from

  D.C. Ramey Piano Company, LLC
  17768 Woodview Drive
  Marysville, OH 43040
  tel.: 1-708-602-3961
  http://dcramey.com/Other%20Items.html 

Don Teach
Shreveport, Louisiana