Using the MODIFY command to save your sanity, plus unveiling the UNLINK command.
 
SCENARIO 1:
You just spent 45 minutes LOGGING a tape (there are no Flex Files or Media Logs, you have done all the work yourself!) and you have a billion nice new Master Clips in your bin screaming to be batch digitized. Now you sit back, sip your coffee, admire your work and you notice: THE DIGITIZE TOOL HAS THE WRONG TRACKS SELECTED (maybe you left on too many tracks of audio, or forgot to turn on the Video , etc.). Ahhhhhh! Do you have to re-log? Naw. Would Avid do that to you? It's an easy fix.

 
1 - First, select the Master Clip(s) you want to fix.
2 - Next, go to the CLIP MENU and select MODIFY.
* As you peek through the menu of things you can modify, there are a couple that are useful in these situations:
A - SET TIMECODE DROP/NON-DROP. Good if you yourself logged the clips incorrectly (just logging from notes as opposed to a tape) or you got the clips logged this way from someone who used MEDIA LOG. You will know you have a problem because you are getting a MIS-MATCH error when trying to batch digitize. Just select this option, choose the correct timecode flavor and all will be well with the world. (NOTE: you can set your default timecode flavor for logging by going to the DECK SETTINGS and choosing the desired flavor from the "When no tape in deck log as:" pop-up-menu).
B - SET SOURCE. This allows you to change the TAPE that the clip references.
C - SET TRACKS. (Finally, here's the solution to our dilemma described above):
Select this option and select the tracks you WANT to be digitized. Selected tracks appear with a double line around them. Hit "OK" and you are back in business.

  
SCENARIO 2:
You just spent two hours LOGGING and BATCH DIGITIZING a tape (there are no Flex Files or Media Logs) and you have a zillion beautiful new Master Clips in your bin dying to be edited with. Now you sit back, sip your coffee, admire your work, and you notice that YOU DIGITIZED THE WRONG TRACKS (oh, maybe 50 minutes worth of avr 75 video when all you really need is just the audio; or maybe you digitized four tracks of audio instead of just one . . .you get the idea). Ahhhh! What now?

 
A - Open the MEDIA TOOL.
B - In your bin, select the Master Clip(s) that are problematic.
C - Using the "Fast Menu" ("Hamburger") that is attached to the bottom left part of your BIN, choose SELECT MEDIA RELATIVES. The corresponding Master Clips in the Media Tool will become highlighted.
D - Click on the TOP BAR of the Media Tool window to make that window active (and this will leave those clips highlighted).
E - Hit the DELETE KEY on your keyboard.
F - A dialogue box will appear. You can now select the tracks you want to delete.
** REMEMBER: Any box that that has an "X" in it means that track WILL BE DELETED.
G - Delete the tracks . . . bye, bye you troublesome tracks!

 
Ok, all is well and good; but you still have clips that say that they have some extra tracks (even though the MEDIA has been trashed, the MASTER CLIPS say that they have audio tracks (or video tracks, or whatever your dilemma). This can be confusing or frustrating to edit with. So, what we will do now is to Modify them. HOWEVER, if you select the clips and choose Modify now, you will get a long-winded dialogue box that tells you that you can't modify them unless they are "Undigitized." This may lead you to think that you need to delete ALL the media. This is NOT the case. Even if you deleted all the media and then tried to modify the clips you would still get the same message.

 
So what's the deal? Basically, Media Composer is protecting you from yourself, as there are times (especially with very large projects) that you unmount some drives to help increase system response (and that media would appear offline). Essentially, the clip knows that at some point in its life it was digitized, and doesn't want you to muck things up. So, what do you have to do? You have to convince Media Composer that the clip(s) have never been digitized (basically that no LINKS had ever been established between the master clip and media files). So, here's the trick.

 
A - After performing steps A through G above, do this:
B - Select the Master Clips you want to modify.
C - Hold down the SHIFT & CONTROL (PC) / SHIFT & COMMAND (Mac). < NOTE: This key combination may differ, depending on your version of software. However, it will always be the Shift key plus either Control or Command.
D - Go to the CLIP MENU.
E - You will notice that the selection that once said Relink, now says UNLINK. Select it.
F - All these clips will now be offline. You have intentionally broken the link between the Master Clip and the Media Files. As far as Media Composer knows, it was never digitized. Woo-Hoo!
G - Now, MODIFY the clips to INCLUDE ONLY THE TRACKS YOU STILL HAVE MEDIA FOR.
H - With the clips still selected, go back to the CLIP MENU and choose RELINK.
I - Bing, bang, boom . . . there ya go.

 
In the previous example we were deleting tracks. This process also works if you have to modify previously digitized clips to include tracks you forgot to log. Then you can go back and digitize the tracks you need, or as Media Composer puts it, "tracks that are unavailable." This is a great time and work-saver if you logged all the clips by hand.