Knock wood have no problem with my machines, anyway I ran into this site of a dutch guy who repairs early Miele PCB (Hydromatic and early Novotronic machines, e.g. W715 ).
He explains why in these models leaving the door crack open also makes PCB last longer :
I had a W715 with that broken PCB, Fixed to put it in the oven [Known GeForce 8800GTX/Ultra Videocard trick] in the oven and it worked again! The solder has gotten off, The oven reflowed it.