The problem with soldering a stranded wire crimp termination is that the solder will wick up into the strands of the wire under the insulation which has now created a small section of basically solid wire. The very reason we use stranded wire versus solid wire is because of it's flexibility. A wire termination at a motor is obviously going to be under a lot of vibration. Constant flexing of a solid wire versus a stranded wire is going to cause it to break a lot sooner than the stranded one. Sure, it may never fail, I'm just saying it's not a good idea. Soldering of terminations is ok as long as you properly secure the wire so that any vibration takes place beyond the secured point and not between the secured point and the termination. My experience is 37 years as an electronics technician with the federal government following rigid established training techniques and documented procedures for wiring terminations. The other problem here is that the average DIY'er doesn't know how to solder and doesn't possess the proper crimp tools to make a proper crimp connection anyway. I don't recommend soldering wire terminations on washing machines.