The Colemans of that era had ABS plastic roofs the developed cracks. Coleman had a special warranty program that would replace the entire roof even after the standard warranty expired, but it was only available to original owners. It would be best to replace it with one of the new roofs, but I don't know what the availability is.
You could check with Fleetwood; they made the Coleman brand then. Other than the roof, they were very good trailers. We had one & really liked it.
2010 Cruiser CF30QB
2003 GM 2500HD, crew cab, SB, 8.1, Allison