
I pulled the current one out and tried to match it but it seems to be smaller than anything any of the auto parts stores stock. Their smallest festoon globes any of them stock is 8mm x 28mm in 3W < http://www.narva.com.au/products/browse/festoon > but the removed globe is shorter than 28mm and is 5W - would be a pity to go lower wattage given the already lacking light produced...
Otherwise maybe an LED replacement globe?