Does the antenna motor make a sound? If so then the nylon cable that psuhes/pulls the antenna is derailed or jammed. Removing the antenna is not too hard, I did mine last week. The problem with replacement is that when you go to look for a $20 replacement power antenna, the shaft is different to the Jepp OEM unit, my advice is to use a multimeter to check for + voltage to the antenna when the radio is turned on, if voltage is present and the motor makes no noise then remove the antenna and take it roud to a few auto shops to find one to match. The shaft is removable from the power antenna assy so you might be able to retro fit it to an aftermarket model. If you do have a sound from the antenna then remove it, strip it, remove all the old lithium grease and other gunk buildup and regrease liberally using white lithium grease. Then use something like WD40 spray to spray the inside of the antenna and the nylon cable, work it up and doen then use an old toothbrush to cleean the teach on the bylon toothed cable. Then regrease the mylon cable and refit. It really isn;t hard at all.
To remove the antenna you will need to locat the power & antenna plugs inside the car close to the front guard, unplug them then locate the rubber grommet and push it thru into the guard. Then remove the inside guard plastic cover, pull out the foam and then use a socket to remove the 2 bolts holding in the antenna assy. Then (or before) remove the nut/ring thing on the top of the antenna and the whole thing will drop down and out.
I went to all this trouble myseld because in Australia we have very limited choices for replaceent and the Jeep dealer wanted US $300 for a new antenna!!! Keep in mind that the actual antenna with the nylon toothed cord is an orderable part on its own if it's teeth are stripped.