Avi with vbr audio to avi with cbr audio keeping it in sync with the video using vdub

Overview: I use vdub twice to get non-skewed cbr audio/video.

I have an avi that has low-level sound with loud distortion; it is a left/right channel balance problem. It is a cam so the audio is hi fi instead of full stereo. I can emulate the sound repair if I click open the volume control in the task bar area of the desktop and move the slider to the left to skew the sound balance towards the left channel speaker. This allows me to check the sound sync on the vdub renderings. I want to get a pcm wave file demuxed so that I can use Diamond Cut 5 to fix the audio – Using DC5 I will either decrease the right channel volume by 1 db or I will make the left channel into mono and then use dc5 to change this mono to stereo using the left channel for both. Either way will give me a good audio that I can then mux back into the avi as pcm wave.

The original avi is vbr audio which when converted directly to pcm with vdub skews the video and the audio out of sync. If the original was in mp3 cbr it would stay in sync when it was converted to pcm wave. I use vdub to do this by:

1 Open the vbr avi in vdub, getting sync skew warning message which I ignore.
2 I set video to direct stream copy and audio to full processing mode, audio to interleaving (in the drop down menu) and click OFF enable audio/video interleaving and then click OK. I then click in the audio drop down menu, audio, compression lame mp3 44100 hz, 128 kbps cbr, stereo, 15 kbs. Gspot had the original at 129 kbps. Then I save the avi.
3 This give you an avi file that Gspot shows as the audio = mp3 iso/mpeg, I then open this avi in vdub and convert it again; the audio to full processing mode, compression to mp3 lame 128 (again). The result when I save the conversion will be audio 128 mp3 mpeg l layer 3 CBR with sync OK which is the desired result.
4 I then open this avi in vdub again and change the mp3 compression to pcm wave. I save the wave for processing in Diamond Cut 5.