There is a screw cover on each side of the unit. These just pull off. They cover usually 4 screws, square head, that hold the unit in. Once removed, it comes out easily. % minute job.
Also to Herk, the booster for the antenna has nothing to do with radio reception. The booster is for the television. and there should be car style antenna on the side or roof for the radio. Need to make sure that antenna is still up there also. One last thing, there is a connection under the car style antenna that may be loose or corroded. Last thought, if you done any mods, drilling, screwing in shelves, etc., you may have shorted the coax line feeding the radio.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT