Have the stock radio/cassette in my 96 Explorer XLT. The on/off went years ago so radio is always on and the volume is lowered when I want the radio "off'". Every now and then the front left door speaker volume is low and adjusting the volume to loud equalizes the volume. Now there is a constant static from only this speaker even when the volume is turned all the way down. Is this an indication of a radio replacement or perhaps a wire shorted in the door speaker? Is this time for a radio replacement and where is a good site for an inexpensive radio that matches original equipment?