It is more difficult to modify a crossing turnout 2275. It is worthwhile to do that, because small locos very often stops because of ground contact problems, specially while driving in the curve. A second problem are the spot contacts. There are less as at the crossing 2257 and short pickup shoes had problems on it. The wires are connected like at the crosing 2257. As shown on the photo I bent a 0.7mm strong wire into a L shape and wedged it under the rail. The lower plastic part and the rail acted like a clamp and established a good electrical connection. Solder the wire as shown on the photograph. This solution is suitable only for permanent layouts.
Switching of the grounded rails occurs in parallel to the activation of the 7549 turnout actuators. Normally you require two 7244 relay, one per actuator. However, since each only requires one switch, I use a modified 7244. You can find the instructions for the modification of the 7244 on page 2: relay 7244..
The connection must be done in such a way, that the actuator for the right side of the turnout changes the polarity on the left side of the turnout. The correct switching, as a function of the turnout position, is shown in the 4 sketches below. It is possible that you need to reverse the cables on the relay.
This graphic shows the 4 ways which are possible. It is easy to see, which power the rails have. Brown meand ground and red means driving voltage like the spot contacts. Small locos has no ground problems not any longer and Roco locomotives with a short pickup shoe can be driven at lowest speed without jerking. If the pickup shoe can not reach a spot contact, it get the electrical power from the rails.