Logitech made a new software for the G29 and 920 wheels and the G27 still uses an older version of the Profiler Software. And there's this bug with Windows10 that it can start recognizing your wheel as a Logitech Driving Force GT wheel instead of a G27.

The easiest way to tell everything is working right with the Logitech Profiler Software and your wheel is that when you plug it in the calibration turns it all the way to the side, then all the way to the other side, then centers it. If it doesn't center there might be an issue.

The other obvious way, is once the calibration is done is to open up the software. It should be running in your tasks in the bottom right and you just maximize it after you're plugged in. When it loads it should show an image of the G27 not a Driving Force GT. The wheel will still work even if it's wrong but a DF GT wheel has way less degrees of rotation and no clutch/shifter or even much FFB I think. So you lose a lot of features if its recognizing it wrong.

I scoured the Logitech forums as well as going back and forth with tech support. There's a few basic solutions that all somewhat work, but many of them seem to not work 'forever' and the issue arises again like a month later. So I basically combined them all and it's worked since.

The basic issue is that it adds new hardware profiles to the Device Manager so its just always going to see a DFGT once it sees it the first time. So you gotta go clean out everything. Starting with the Profiler Software.

1. Unplug your G27 from your computer.
2. Uninstall the Logitech Profiler Software through Windows' Programs & Features.
3. Then download and run WheelDriverCleaner.exe ( http://chilp.it/c09316a ) This is Logitech's program for removing hardware drivers for the wheel.

Next is to remove all "ghosted" entries for the wheel in the Windows Device Manager.

1. Run a Command Prompt by going to the Start Menu and typing CMD and opening it.
2. Enter the following;

set devmgr_show_nonpresent_devices=1

this will tell the Device Manager to show any devices that may be hidden beyond normal in some facet.
3. Then open Device Manager. (you can launch it from the Command Prompt by typing; devmgmt.msc or open it through the start menu)
4. On the Device Manager menu click "View" and then "Show Hidden Devices"
5. In the main window click to expand the categories "Human Interface Device" and "Universal Serial Bus Controllers".
6. Under these two categories Right Click then "Uninstall" each and every one of the greyed out entries having to do with Logitech, Racing Wheels, DFGT, G27, etc.
7. Give the computer a good ol restart at this point.

Your computer should now be wiped clean of any traces of the Logitech software or hardware. But that's only cleaning up the problem. Now you have to install it in a way that (hopefully) Windows will not repeat this error.

Download the v510 of the Logitech Profiler Software from the Logitech website( http://www.logitech.com/pub/techsupport/joystick/lgs510_x64.exe ). The story goes that when Logitech first upgraded to their latest software they removed the 64bit version of v510 so you'll run into a lot of old information with links to third party sites with a bunch of different v510 exe's of varying sizes and other things that make you question its validity. But the problem seems to have been rectified and the v510 64bit is indeed on Logitech's website once more and obviously would be the safest bet to download.

1. Open the install and let it unpack BUT DON'T CLICK ANYTHING!

The theory is that during installation something happens with this file (or doesn't happen) and its why Windows 10 starts thinking DFGT when you plug in the G27. Or something. But you need manually install a driver file before installing the software any further.

1. In Windows 10 go to the folder; C:\Users\"YourUserName"\AppData\Local\Temp\ (This is where the install unpacked to when you opened it).
2. Do a search with Ctrl+F keys and search for a folder named 2b-LGS-x64
3. There may be multiple folders since you probably have installed this software before. Choose the most recent one. And navigate within it to the folder; ...\Common64\Logitech\WMDrivers\
4. Right click on the file named wmjoyhid.inf and choose "Install". It will be very fast and there may or may not be a prompt saying installed. If there is a prompt to restart do not restart for now.

Now its time to return to the Logitech Profiler Software installation.

1. Follow the directions normally and plug the wheel's USB in when it tells you to and all that (make sure the wheel power cable is already plugged into the house/wall power. And remember, USB 2.0 is prefered and try to always use the same USB slot every time you play).
2. When the software install is complete unplug your wheel and restart your computer.

And the final test... Did it work?

1. Let the computer start all the way up.
2. Make sure you got power cord plugged in again obviously and then plug that USB in. Wheel should calibrate like explained above and Profiler Software should open and load to a picture of that beautiful G27.

And you're off to the races!