I picked up my Pere Marquette Berkshire last week. My main purpose was to use it to pull my Polar Express passenger set. I got the Pere Marquette version as I already had the Polar Express tender and I wanted to use the Loco for other purposes with the Pere Marquette tender. There was a question a few weeks back about the potential difference in the location of the infrared coupler on the older tenders and the new engines.
As expected the new Berkshires place the sensors on top of the drawbars. The old tenders have the larger sensor circuit located on the bottom of the drawbars.
After verifying that the old sensor works fine with the new locomotives I decided to reposition the tender sensor on top of the drawbar.
First I cut off the shrink tube holding the wires to the drawbar.
Then I removed the two screws holder the sensor to the drawbar. I also rotated the flat keeper plate out of the way In case I want to put things back the way they were.
My original intent was to just flip the sensor over and screw in in from the bottom. Unfortunately the two screw holes are not positioned symmetrically. I therefore had to just translate the box to the top of the drawbar. This meant that the cover of the sensor box which had been against the bottom of the drawbar before was now on top and loose.
So after making sure the plastic window was still in place
I simply put the cover back on top…
Covered with a piece of shrink tube…
And applied a little heat.
Now I can run either tender with the locomotive depending on what I am pulling.
Enjoy the videos.
They're small Phillips screws, probably #0. 
