A I haven't done much work on the 1200GS, but my understanding is that the older ABS equipped versions, those built before 2007, do require special tools and techniques to bleed the brakes and even to change the fluid. The problem, and again this is based on limited experience is that the ABS computer "see's" the brake bleeding process as a leak in the system and shuts off that portion of the circuit. You then need to reset the computer using the BMW diagnostic tool. So the problem is two-fold in that you need to bypass the ABS to bleed the system, and then you need to reflash the controller. It's a little too complicated for my tastes, I'd recommend a non-ABS version if you want to work on the brakes yourself. Starting with the 2007 models BMW went to easier to service ABS, called I believe ABSII. Those systems are much easier to work on, and from what I've been told, require no special tools to perform routine maintenance.