For many years I have used a tip I read online about disabling the electrical switch mechanism in the Märklin K-track turnout motors. As I made the modifications to my last few motors I decided to show what I do and took some pictures of the steps.
Note that over the years the shape of the Märklin 7549 turnout motors have changed. This post applies to the older version which can still often be found at train fairs and the second hand market.
The turnout motor comprises two solenoids that pull the mechanism in either direction. The design includes an electrical cut-out to prevent the coils from remaining energized after fully actuating. This prevents the coils from overheating and melting the plastic thus allowing the motor to survive being switched with continuous current. Unfortunately the physical switch adds a tiny amount of load to the mechanism and this sometimes causes the motor to not fully switch. Since I switch all my turnouts with a pulse (and my software is stable enough to not forget to switch the current off after each pulse) I remove the physical switch to reduce the possibility of needing to pull the motor out of the layout due to failure.
In addition to removing the switch, I also lubricate the mechanism with graphite powder.
The plastic cap of the switch motor simply pops off revealing the two coils and the mechanism that slides up and down.
Removing the two switches
Once it is pulled up past the plastic slider, I fold it back and forth to cause it to break off at the circuit board due to metal fatigue.
Three or four motions left and right are normally enough to break it off.
Now, since I have removed the switches, current from the yellow wire can never reach either coil. So I have to bridge the connection on the left and right.
Fortunately there are solder pads I can use! I bridge the two pads marked A and B where the red line is in this photograph:
I do the same on the left, making sure that the yellow wire remains connected.
If I find that I end up with a big blob of solder bridging the pads, I check that it does not foul the end of the moving mechanism. If it does, I simply snip off the end of the plastic as can be seen above.
At this stage it is prudent to test that the motor actuates in both directions. I hold the bare end of the yellow wire onto a yellow wire from a 16V AC transformer and then alternately ground (brown) each of the blue wires for just a moment. As each blue wire is grounded it should snap the mechanism left or right.