The leadscrew is 16mm and these are 16mm :-(
http://cgi.ebay.co.uk/66300-HOT-BODI...item5889f42ca0

These will do but the price will not...I only need two,not 16 :-(
http://cgi.ebay.co.uk/86764-HPI-SHOC...item5889fc27bf

The tension looks about right? can't have it too stiff,could cause a problem on the autofeed?