You could try rubbing it over with eucalyptus oil if it cant be submerged. Tea tree oil sometimes reacts with plastics... partially dissolving the surface making it look dull... eucalpytus oil is a little bit more gentle but just as harsh on bacteria if that is the cause.
opps, already tried the tea tree...made no difference to the smell though. i think its just the way the plastic smells, it has a little play table thingy that comes off and i have literally scrubbed it with all sorts and as soon as it dries it smells the same! guess il just have to get used to it! thanks though.