This is a killswitch to replace the Yamaha 1986 BW200ES but should work on all BW200 models (Not sure on the BW350 but you can try).

I recommend after you re-seat the killswitch onto the backing plate (little metal piece shown), that you keep it half assembled and test the killswitch connections with your BW200. I had to adjust and bend the metal until the ‘Off’ position correctly killed the engine as originally bending it to get the broken switch out, put it out of place from its original position. 

The process is fairly straight forward though. This may work with other yamaha kill switch's, but I am unsure. I used ASA and made the print quality ultra fine with some small supports. Even then it was only a 20 minute print. very small item. But worked well!