HK Subwoofer Grill replacement

Hey...I'm a newbie to the forum but have been here for the past 3 days carefully reading all the threads concerning care/effect/replacement/fixes for the HK subwoofer. Good Stuff.
I own a 2001 Z3 3.0i and have been doing some interior detailing and repair on it.
I'm in need of the HK Grill that covers the front of the subwoofer compartment. The part number stamped into the plastic reads 51.16-8 398 959 but I cannot find this anywhere on the internet. The problem is that part of the foam material that sits between the metal grill work and the plastic back has deteriorated leaving unsightly inconsistencies while looking at the face of the grill. (Yes, I too am probably OCD about my Z3)
The metal part of the grill is attached to the plastic back by 12 metal "tabs" that are easy enough to bend out, but it is also attach to the plastic back by crimping the entire overhang of the metal frame around the plastic. This has proven impossible to disengage since putting it back together would be next to impossible for me. This seems to leave replacement as my last alternative. I have called some local yards that carry wrecked/damaged Z3's but no one had the correct model with the correct grill.
Does anyone know how to get this part or have one available in great condition? Has anyone altered or repaired theirs in much the same way as I am trying? Any solutions?
Thanks

My solution to my H-K grill foam deterioration was to remove the grill, remove all the remaining foam (including a good vacuuming), and then popping the grill back in. It looks fine. Yes, you can see the speaker through the grill, especially if the suns shines on it at a certain angle, but the grill looks neat and tidy again. Problem solved.

Same problem with grill and I did just what BeemerMikeTX suggested. The grill cleans up very nicely and, if needed, some light matte black spray paint can take out any discoloration or unevenness. My car had been sitting under a tree in Vermont with various sap drippings, including a nice one on the grill, which are very resistant to removal. A very light sanding and a quick spray made it look very sharp. I like seeing the speaker through the grill, particularly with the inexpensive silicone foam repair which shows up as a white ring.

I'm sure you have seen in other postings, but be very careful with the plastic tabs. They are brittle and easily broken upon reinsertion.