Tone blocks and dead spots

My Streamer M4 has a dead spot on the 9th fret of the g. Adding weight on the head stock doesn't seem to be much of an option. There is what I guess is a "tone block" underneath the bridge that has a hollow area in the center of it. Would it help to alleviate the problem if I was to fashion a lead( or more favorable material such as brass?) weight to fit in/fill this area adding more mass/weight?
This dead spot seem to affect the 8th fret just a tad also. I love the tone of this bass but this problem takes a bit of the fun out of it.