I am suprised that the manual says that. The drain pump (which is most definately not the cause of your fault) can be accessed from the front, however that needs the door front panel and the large lower plinth and a few other bits removed to gain access. There is access to the flap valve of the drain pump from inside the dishwasher, under the filter but I say again, this is unlikely to be the cause of your problems. You cannot access the circulation pump without a major strip down involving removal of top, door, side panels and complete inner tub. There is a hose that often gets blocked that you can get at in the same way as the drain pump. it runs right across the left lower front of the machine but once again is really best left to someone with experience.
That which can be asserted without evidence, can be dismissed without evidence.