Narrowall Model 500-D wall furnace-gaskets

I had the gas man come out to turn on pilots on two wall heaters. I bought the home in July 2012. The heaters were red flagged previously and after checking, everything works except it needs gaskets. So he did not leave pilot on (understandably) because "product of combustion are spilling at the gasket area into living quarters". Since all works except needing gaskets, where can I find gaskets for this kind of wall furnace because it's very old and I can't yet afford replacing the heaters. Any tips will be appreciated.