Do not know if this helps any, but see this post on replacing roof vents it shows what was under mine and some of the frame.
Replacing roof vents 101
Do you have rubber or alumunimum roofing?
If the wood is moldy/wet, I would deal with it for sure when you have the vent off and make sure it is dried out before putting the new vent on. If the wood is real bad and verses tearing up the camper, they do make a product called Rot Doctor. You put this on over rotted wood to seal it and make it stronger. http://www.rotdoctor.com/
Yes pic's will help
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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