I'm sure I saw replacements on line somewhere. Probably worth a 1.50, but 10 from a vendor with shipping, however sure seems easier. My dad once designed and built a machine to wash those for GM, it was big and I wish I knew more, but he passed before he could explain it to me.

Eric
http://s1199.photobucket.com/user/sparky234/library/My%2057%20Chevy%20Stepside?sort=3&page=1
'57 Chevy 3100 (Little Red)
'81 RD350 LC - Fun, Fun, Fun
'83 GS1100E - Pocket Rocket