1. Turn your AV, or AV Shields OFF.
2. Right click on the 727 installer, and select 'Run as administrator' from the list.
3. Select the 'Repair' option.
4. Reboot your computer.

After the computer reboots:
1. Turn your AV, or AV Sheilds OFF (if they came back ON after the reboot (mine do)).
2. Run FSX
3. Load a Captain Sim 727, and see if everything is there and working.

If everything is working like it should, all the gauges visible and working, exit FSX.

1. Turn your AV, or AV Shields ON
2. Run FSX
3. Load a Captain Sim 727, and see if everything is still there and working.

If it is, then your problem is solved. If they aren't, then your AV is probably blocking the gauges from working*. You will need to add the FSX installation folder to the exclusion list of your AV. Doing that will stop your AV from blocking the gauges from working.

If FSX is installed in it's default directory, C:\Program Files (x86)\etc... then that alone can lead to trouble with advanced addon aircraft for FSX. It is always best to install FSX anywhere else but the default location. C:\Microsoft Flight Simulator X is good, but on another partition would be even better.

I always run FSX using the option "Always run this program as an administrator". This gives FSX the ability to do all the things needed to do to make everything work like it should when using an advanced aircraft addon.

* The gauges might also have been removed and placed in the AV Virus Vault/Virus Chest. You will need to click on them and restore them to the  directory they were removed from.