The Cobra 75 WX ST's are not known for their durability... A few Jeep friends have tried using that radio due to its compact size, but sooner or later either the dust, heat or being knocked around damages one of the components in the mic; since most of the components are in the mic.
You might get lucky by taking the radio to a local CB shop, but my suggestion would be to sell it on eBay as a Tech Special and buy a better radio.
Depending upon what your needs are in a CB radio; there are a lot of good radios out there. The Cobra 25 & 29 and Uniden 66 & 78 are good AM radios of moderate size that can be modified for good performance.
2000 Ranger 4.0L 4dr 5 spd 4x4 w/ ORP
Modifications: 265/75R16 BFG AT KO, Detroit TruTrac l/s, K&N FIPK, 66mm BBK TB, Gibson 2.5" catback exhaust, BAMA SCT Tuner, Underdog Performance 25% underdrive pulley, James Duff Traction Bars, Taylor 8mm sparkplug wires
Future Mods: JBA Headers