Hey Sveifors,
Ignoring the possiblity of simply a sticky hinge at the end of the pickup arm, or an iffy control servo, have you considered that it may be a dirty or disfunctional "laser eye"? I believe the whole point of these was to prevent the stylus being lowered onto a bare platter, and if it is playing up I would probably expect symptoms like those you are describing...
And by the way, your English is infinitely better than my Norwegian.
...er.... kan jag be at far en kappe caffe?...
Alex
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Beowulf - the Original music aficionado...?