Usually, if the front comes on and does not flash, the rear is burned out, or not making a connection. Usually, the flasher needs enough of a load to flash, a feature to let you know that you have a problem somewhere in the circuit.
Good point, I was ASSuming he meant the marker worked but not the directional. Some clarifacition may be in order. Some systems falsh faster if 1 bulb is out while some come on solidly. Still, how do you access the front marker/turn signals if that is the problem? I have not needed to do it yet, but would right there with the OP and simply remove the inner fairing on that side. Is there more to it?