Chosen Solution

Thomas will not go round corners as the rubber bands have split. Anyone know if replacements can be bought?

There are companies that sell large sized rubber bands. Perhaps something from a camping shop? http://www.rubberband.com/about-us/rubbe

Ebay :-) http://www.ebay.co.uk/itm/RUBBER-WHEEL-D

just buy a few rubber wrist bands & stretch them over wheels & into grooves put at least two or three each side it works

Some rubber o-rings from a parts store might work.