My experience with my '83 126 body is that water leaks down the shaft of the electric motors for the front windows which eventually locks up the motors. The culprit seems to be water leaking past the end play adjustment screw for the armature of the motor (it points upward in the installed position). On the last two motors I have replaced I have caulked this adjustment screw as a precaution but can't report whether has helped. The "vague ticking" you hear is the locked armature receiving power. If the windows are used frequently they will continue to work indefinitely but if you don't use them for a period of time (like during the winter months) they will cease functioning. I have disassembled these locked motors and freed them up without problem but the armature shaft is invariably too corroded and pitted for my tastes to permit a reliable grease and moisture seal. As for the passenger side, if it's not "ticking" it may still be the motor but is probably the fuse or switch.