Sometimes it can be easier to do something for a friend rather than explain what they need to do. Is it possible for you to simply copy your working program files for them to use?
The challenge they may be having is this. I don't know how close "nearby" is. The database shows this system as having a range of 15 miles. So they might be shut out of monitoring due to range operation.
Another consideration is even if the 15 mile Range can be overcome with either increasing scanner Range value or changing the range values for a Sentinel Favorites List, they might be beyond "transmitter reach".
To add slightly to what ofd posted, is presuming that your 436 works (that is, you have the 436, and not a 536HP being used on an external antenna), would it be possible for you to take a short drive over to their area & see if you still have reception? As mentioned, depending on the distance, as well as whether you are using location control, you might need to increase your range to make sure Columbus is receivable. If, using your current setup (making any range or location control correction as needed), you can monitor the Columbus system on your scanner, then you've confirmed that it can be done. If you cannot, then that confirms what ofd001 suggested, that they may simply be out of receiving range. To avoid being hijacked by one of your friends to "stop by & look at my scanner", you may want to make that an unannounced journey.
In my area, the DFW Metroplex, several of the systems that switched to Phase II have basically gone from in-range to me, to out of range. When the conversions were done, there were several changes made that reduced the coverage footprint. For thing, the transmit antennas used were oriented to direct more of the signal down into the jurisdiction area. In the case of Grand Prairie, they also lowered the antennas on the towers, as well as reduced the transmit power.While that city is less than ten miles from me, I've gone from being able to easily monitor their old Motorola Type II system to not hearing them most of the time, even on a scanner connected to an external rooftop antenna. The same happened with Arlington & Irving. Previously, no issues, even on a handheld. Now, scattered reception only if using a rooftop antenna.