Changing out an NH35a movement is really easy for someone that likes to tinker with watches. You will need some basic tools and you will need some training that you can get by watching some DIY YouTube video's. If you aren't interested in learning some watch making skills than it isn't worth doing. My suggestion is to buy the movement you need online and find someone to do the swap. Its not worth the frustration for the average person. You have to spend some time learning basic skills in order to do this swap correctly.