Radio sound problems

There is a tech buuletin on your truck for the radio, it probably applies to you, here's part of it. Take this to your service dept and see what they will do for you.
AUDIO / NAVIGATION SERVICE AND ORDERING PROCEDURES
TECHNICAL SERVICE BULLETIN
Reference Number(s): 06-21-7, Date of Issue: October 30, 2006
Superceded Bulletin(s): 06-10-10, Date of Issue: May 29, 2006
Related Ref Number(s): 06-10-10, 06-21-7
ARTICLE BEGINNING
ISSUE
Some vehicles may require the audio or navigation unit to be replaced. A new Service Procedure is
available for vehicles listed in the Vehicle Application Chart (Fig. 2).
ACTION
After performing diagnostics to determine if replacement of the audio or navigation unit is necessary,
follow the Service Procedure to obtain the part number for ordering. Removal of the audio or
navigation unit to access the part number is no longer required.
SERVICE PROCEDURE
The part number can be accessed on the audio display head / screen. There are two different
procedures for each subsystem, select the one that applies.
AUDIO PROCEDURE 1 (CD-6 WITH NEW ROUND CONTROL BUTTONS (FIGURE 1)
Fig. 1: CD-6 With New Round Control Buttons
1. Turn the radio "on".
FORD:
2005-2007 Crown Victoria, Five Hundred, Focus, Freestyle, Mustang; 2006-2007
Fusion; 2005 Explorer Sport Trac; 2005-2007 E-Series, Escape Hybrid, Escape,
Expedition, Explorer, F-150, F-Super Duty; 2007 Edge, Explorer Sport Trac; 2006-
2007 F-650, F-750
LINCOLN:2005-2006 Lincoln LS; 2005-2007 Town Car; 2006 Zephyr; 2007 MKZ; 2005 Aviator;
2005-2007 Navigator; 2006-2007 Mark LT; 2007 MKX
MERCURY:2005-2007 Grand Marquis, Montego; 2006-2007 Milan; 2005-2007 Mariner,
Mountaineer; 2006-2007 Mariner Hybrid
NOTE:
This article supersedes TSB 06-10-10 to update the vehicle
applications as this procedure doesn't apply to the following vehicles
if equipped with the Navigation System - 2005-2006 Expedition, 2005-
2007 Escape, 2005-2007 Escape Hybrid, 2006-2007 Mariner Hybrid.
NOTE:
THIS TSB DOES NOT APPLY IF THE DISPLAY HEAD IS NOT
FUNCTIONING.
2. Press and hold the memory preset buttons 3 and 6 for 3 seconds - this will initiate the speaker
walk around test.
3. Before the test is complete, press the button 6.
4. Then press the up-arrow on the right hand side of CD slot to view and record the part number.
5. To exit, turn the radio "off".
AUDIO PROCEDURE 2 (ALL OTHER UNITS)
1. Turn the radio "on".
2. Press and hold the memory preset buttons 3 and 6 for 3 seconds - this will initiate the speaker
walk around test.
3. Before the test is complete, press the button 6.
4. Then press the arrow on the right-side of either one of the following buttons: "disc", "tune", or
"disc-tune" depending on the unit - this will display the information menus that scroll through
the following items quickly: config 1, config 2, eeprom number, and audio part number.
5. You may have to repeat Step 4 a few times to capture the part number completely.
6. To exit, turn the radio "off".