Only Marflex can tell you about what they can still fix on a Linhof Color. I find it's usually easiest to reach him in the morning.
They can grind cams for Tech IV and V, but not III. Richard Ritter grinds cams for the Tech III.
Even if you have a Tech V, it's a good idea to send the camera in when you have a new cam made, so Martin can install the stops and scales, check the rangefinder and groundglass calibration, and do a general CLA, if the camera hasn't had one in a while. It's probably best to ask Marflex what the current charge is, and it might depend on what else the camera needs, since he might find other parts that need to be replaced when you send it in, or he may be able to otherwise improve the setup of the camera by doing things like shimming two lenses so that they can use the same set of infinity stops (135/75 and 150/90 are common combinations).