Rear windscreen wiper Y

The tail wiper of my Y 840 from 1999 is on strike. Now I have the cover of the tailgate down and measured the voltage at the connection plug. If the wiper is switched off no voltage, so it should not be a cable break. Then I took down the cover of the mechanics and discovered that a kind of clamp with spring on it has broken off, which goes from the lid to the inside. The clamp seems to be in front of the drive screw of the electric motor g What is the purpose of this? The question is, how do I best proceed now? Build mechanics apart and see if the engine turns freely? (If so, how best to proceed?) Have taken pictures to illustrate MFG Finntroll