There is one way to fix this kind of problem and that is with a program called FSPANELSTUDIO
This is a payware software but it is by far the best tool one can have for fixing and adding both new gauges and windows to existing aircraft in both FSX and FS9
This program uses a process called WYSIWYUG which stands for What You See Is What You Get.
When using this program it shows you the actual panel you would see as if you were in the sim itself. To add a gauge could not be any easier all you have to do is to find a spot for the gauge click on the spot than stretch or shrink it to fit
there are no coordinates needed.
This program spots gauge problems real quick all you have to do is to click on any gauge you see and the program will tell you what gauge file is being used or if it is undefined.
here is the link http://www.fspanelstudio.com/
Trust me you can not go wrong with this program. If you do any kind of additions to aircraft windows or gauges this is the program you want.
There are people here other than myself that use this program they will back up anything I have said here
There is a try before buy option if you are unsure.
With this program you will be able to make any change to any panel in your fleet. It even creates and edits XML gauges.