Yes, you heard right! I've managed to fix that awful trim problem. I've added a bunch of other fixes & enhancements too:

Note: These modifications do not require the V-One gauge to be installed.
Any user with a modified flight model will need to adjust the CG offset for proper auto elevator trim.

Now available in the Avsim Libray, search for:
Boeing 727-100/200 Various Fixes

- Airspeed Indicator Enhancement
- ADI & Flight Director Corrections
- A/P Enhancement for Flight Director
- Radar Altimeter Fix
- TAT Display toggle via DME Indicators
- Trim Sensitivity Fix
- Auto Setting of Altimeter Alert & Elevator Trim
- GPWS Switch Fixed
- NAV/GPS toggle via Marker Beacon Sensitivity Switch

Many thanks to Markoz for you time and testing 

There shouldn't be any issues at all. Give it a try and let us know 

An update to the installation:

The XML files are in the wrong directory for the -100F, -200 and -200F.
The -100 is in the correct directory.

The '727_various_fixes.xml' needs to be moved to each respective \panel folder:

FROM:
..\Microsoft Games\Microsoft Flight Simulator X\SimObjects\Airplanes\CS_B727-100F
TO:
..\Microsoft Games\Microsoft Flight Simulator X\SimObjects\Airplanes\CS_B727-100F\panel

Repeat for the -200 & -200F

Sorry about this but errors can happen 

Looks to be an awesome fix. I will try this next time I do a serious CS727 flight.

Thanks, fsxpaul.

And thanks for all your help with testing Mark 

Hi Chris,

The auto-trim is released when the wheels leave the ground, trim will adjust whenever you command after that.
But I did find an error that was locking the auto-trim while still on the ground.

Add the following RED item to the 727_various_fixes.xml in the <!-- Auto Trim Set --> section about 40 lines down in the code:
(L:TCAS_P13_008_BUT_POS_click, bool) (A:BRAKE PARKING INDICATOR, bool) and (A:SIM ON GROUND,bool) and (A:ENG HYDRAULIC PRESSURE:2,pounds) 0.0001 * 2800 &gt; and

Make certain to have a 'space' on either side.

I'm very confused as to why the trim is locked at 0? That's not happened to me in all of my testing.

Are you using FSX SP2 or Acceleration?

Did you make any other changes to the 727_various_fixes.xml file?

Are you using the Auto Altitude Alert set?

Well, I just added the "and" as per your instruction. When it didn't work, I deleted the whole Auto-trim section. This worked trim-wise, however, the whole steering (front wheel, rudder, ailerons) was out of order.
Therefore my question, if there was a way to delete the Auto-trim while keeping all the other goodies.
Chris

PS: Maybe this has nothing to do with the problem: After start-up, I have to push Ctrl E in order for the GPS to work. (electrical state?)