Gray and white areas in M76 narrowband image

[Bob Hertel]

I'd like to find a way not to have areas of white/grey in this image
https://dl.dropboxusercontent.com/u/97110357/M76.fit

My processing was
Pixelmath Hubble Pallette, calibrated and aligned masters,weighted  as follows:
S*.5 + H*.5
H*.15 + O*.85
O
Dynamic Crop
ABE
HT
HDRMT
TGVDenoise
Saturation curves.
Scope was a TEC140, ATIK 8300 mono camera

Here are the master frame specifics, along with the combine:

S:  35x30min  https://dl.dropboxusercontent.com/u/97110357/S.fit
H:  38X30min  https://dl.dropboxusercontent.com/u/97110357/H.fit
O:  32x30min  https://dl.dropboxusercontent.com/u/97110357/O.fit
M76 SHO       https://dl.dropboxusercontent.com/u/97110357/M76.fit
Could someone please have a look/suggest what I can do?
TIA,
Bob Hertel