Okay, I know someone was looking for a t-shirt plate for a White earlier, and I came across this:
http://www.bonanza.com/booths/sousew...Plate_w_Screws
I don't know if it will fit, but it might be an option, looks to be the same mechanism. This is the same place I got my Greist zigzagger, and I just placed an order for some more White parts.