Matt and JP,
the fuel damper is just a damper, not a regulator; it's just a thick rubber diaphram between the metal halves. I replaced the diaphram on mine and the old one looked perfect. I think Naj may have had the same experience. Easy enough to do, so what the heck.
If the banjo bolt is stuck, I suppose there are a couple of options. First, replace the whole thing; I'd look for a used one. Second, cut around the banjo end that the bolt goes through to relieve the pressure on the threads, with luck it will then come apart. Third, remove the unit and fill the chamber that connects to the banjo with pentrating oil, let soak, hit it a few times, and hope that loosens it. Good luck!
George Davis
'69 280 SL Euro manual