I was cleaning my recently acquired Necchi, and I ended up removing the wheel and saw that the wick had deteriorated and was causing problems. I have been wick hunting all day and finally found a place and thought I would pass it along.
Google McMaster-Carr>
Scroll down until you see raw materials>
click on felt, when that page comes up>
on left side bar click on cord, when that page comes up>
click on extra firm white F1 and then choose the diameter you need.
At 5 foot lengths it should last awhile.