Hello Catherine,
BSK have a shop on eBay where they sell all kinds of knitting machine related items - they stock sponge bars.
Metropolitan advertise them on their website www.metropolitanmachineknitting.co.uk
Uppingham Yarns advertise in Trading Post in Machine Knitting Monthly
I'm sure you will be able to get one from one of these companies.
Regards,
Sue
October 2010