Assuming that spares for the kit are not available and not knowing the manufacturer my method would be to put the model on a very simple diorama base with the tank sat in mud or soft earth and put the joint at the bottom. I would then arange the mud or soft earth to cover the joint or gap in the tracks at the bottom so that it can't be seen.
I can't think of any other way of dealing with it really but that would work very well.
For a bit of inspiration have a look at these pictures:
http://www.scale-models.co.uk/showth...t=3430&page=12