I have a Pfaff 130, and all I can say about the bobbin insertion is that it is something you need to learn to do blindfolded, and that comes with practice. The machine is so heavy that tipping it to put in the bobbin almost takes two hands. Mine is in a cabinet, and there is a hole/opening in the cabinet to stick your hand through for purposes of reaching in to place the bobbin. Obviously a person can see nothing when using the cabinet opening.
I am assuming since you said the machine had been serviced that you do have the bobbin case.
One helpful hint is that the bobbin case lever, which is held in the open position when inserting the bobbin needs to be positioned at the 3 o-clock spot (middle of the right side of the circle). If you have it in any other position, the bobbin case and bobbin will drop out. In the case of my cabinet, I am then on the floor looking for it!