I finally figured out for myself: yes, this modification can be done on an LW, and it's not too difficult.
With the top of the transformer core exposed, I discovered that the transformer core can be rotated 180-degrees (as viewed from the top), which effectively changes the transformer to right-hand rotation because the wiper arm will sweep across the exposed windings in the opposite direction. I had already done this on a simpler Lionel model "A" transformer, as noted previously in this thread. Using this method of modification on an LW, the various transformer taps will maintain their original values and there is no re-wiring of the whistle control circuitry.
Here is the general procedure for modifying an LW:
Open the case and remove the top frame from over the transformer core (this requires straightening 4 metal tabs). Next, drill out the rivet heads that secure the transformer to the base frame. The rivets are a long double-ended type that also hold all the transformer laminations together.
Next, drill out the other end on ONE rivet and remove the long shaft that goes through all the transformer laminations, and re-fasten with a 8-32x1.5" machine screw and one nut on the bottom, extra threads sticking down. Then replace the second long riveted shaft through the laminations the same way.
Re-orient the transformer core 180° (as viewed from the top), lengthening two wires as necessary (this will become self-apparent at this stage). Then re-fasten the transformer core to the base frame with a second set of nuts on the long machine screws. The first nuts serve as suitable spacers and the transformer core unit can be re-attached to the base frame with another nut on each screw.
The exposed top of the secondary windings will need to be polished lightly for the wiper arm to make good contact on its new, different arc. Then re-attach the top frame. One trick with reassembling an LW at this point: make sure the contacts for the direction button are correctly positioned when the top frame is reattached to the base frame. I used long machine screws to reattach the top frame to the lower frame, so I don't have to bend the four tabs if I work on it again.
As you can see in the photo, I have a home-made control knob on my LW, made from copper pipe and a piece of wood cut with a hole saw. The original plastic knobs and levers are prone to breakage and original replacements are somewhat hard to come by. I prefer my round home-made knobs, anyhow.
Now my LW has a control knob with right-hand rotation like the RW next to it, and it works fine this way. I used to have occasional mishaps in train handling with the control knobs operating in opposite directions on side-by-side transformers. No more of that! The FRA should establish some basic standards for train control equipment!
This LW is now a most-favored transformer, because it packs a generous 125 watts of rated power. That's good for about 90 watts continuous according to the old Lionel guidelines. It will effortlessly cruise two trains (with 3 motors) around my big mainline circuit, and blow whistles and horns.
Maybe I better add a safety disclaimer: don't work on these transformers unless you know what you are doing!
