when my 932M-PDF arrived last week, I cleaned all the preservative off and also opened up the column and cleaned the inside and removed all the grease and re-greased with Belray. the next day after I had mounted the mill on the stand I found this on the floor about 2 feet from where I had done the cleaning. anyone recognize this? has me stumped. it feels somewhat polished, is slightly concave on one side and slightly convex on the other. there was no grease or oil on it.