Quote:
It happens when the rolling machine's belt gets dirty, causing Planchets to get dirt and grime on them.
I'm not so sure about that. I thought the rolling machines were used to roll the blank stock sheets to proper thickness and the steel rollers would some how get grease on them and roll the grease streak right into the blank stock. Then the blanks were punched out with the roller lines on them. Then the rest of the minting process used the streaked blanks.
If I'm wrong sombodey let me know, thanks.