Radio Shack 120-2130A - Manual (Page 18)

Clean the tape head after about every 20 hours of playing time. Insert a
special head-cleaning cassette, and follow the cassette's direction to
clean the tape head. Your local RadioShack store offers a variety of
cassette player head cleaners.
Restoring Tape Tension And Sound Quality
After you play a cassette tape a few times, the tape might become tightly
wound on the reels. This can cause playback sound quality to deteriorate.
To restore the sound quality, fast-forward the tape from the beginning to
the end of one side, then turn the tape over and completely fast-forward
through the other side. Then loosen the tape reels by gently tapping each
side of the cassette's outer shell on a flat surface.
CAUTION: Be careful not to damage the cassette when tapping it. Do not
touch the exposed tape or allow any sharp objects near the
cassette.
Replacing A Fuse
If the stereo does not operate properly, you might need to replace the red
power wire's fuse with the supplied spare fuse.
If the clock resets or stored stations are lost when the ignition is off,
you might need to replace the yellow continuous power wire's fuse with the
supplied spare fuse.
CAUTION: Do not use a fuse with ratings other than those specified here.
Doing so might damage your stereo.
WARNING: Before you replace a fuse, disconnect the cable from the vehicle
battery's negative (-) terminal.
1. Hold the fuse holder by both ends, push the ends together, twist one
end counterclockwise, then pull them apart.
2. If the fuse is blown, replace it. Use only standard 1-1/4 x 1/4-Inch
fast-acting fuses with the proper rating. The yellow + 12V TO BATTERY
wire's fuse must be 6 amps (such as Cat. No. 270-1012), and the red
+12V TO IGNITION wire's fuse must be 0.5 amps (such as Cat. No.
270-1003).
CAUTION: The supplied fuses have the proper ratings. Make sure you
replace a fuse only with another fuse of the same ratings.