High beam does not snap in, remains weak

Moin, am quite new here, so first of all hello to everyone! With my Volvo V40 Bj 2001 the main light does not snap after I pull the lever over stage 1 after stage 2. The light horn comes however. That is the same light as the main light, right? At the same time the bulb of the main light stays on, but only very weak… A mechanical problem is probably not or should a mechanical snap be noticeable at the lever? Oddly enough, it is also the case with me that when the main light lever is switched off, the dipped light (and not the main light) is correctly snapped in. If the engine is running again nothing. I pull the lever back (out of the first resistor of the light horn) and the main light goes on, while releasing again. Thank you for your answers! Pyfo