Technics SL-10 Intermittent cueing problem

Hello, I am the sole owner of a Technics SL-10 turntable that I purchased back in the 80's when I was stationed in Germany with the US Army. The turntable still operates but has come up with a cueing problem that is intermittent that happens with regularity.  When the play button is activated the stylus cues as it should, the LP starts playing then it stops playing - the stylus lifts off the LP and returns to its detent position.  This same problem occurs at various points throughout the playing time of the LP.  Infrequently, the turntable operates as it should and plays just fine through the entire side of LP.  I took it to Los Angeles for repair by an outfit that has expertise with this particular turntable but I'm not confident that the technician can find and fix the problem.  I picked it up from this shop 2 weeks ago with a $400 bill that showed that a belt had been replaced along with a few other adjustments but it is still doing the same thing.  I took it back and the technician is ordering another belt from Japan - supposedly, the one designed for this turntable.  He used a makeshift one initially.  To me, the problem sounds more like a faulty sensor and may be out of the scope of this technician's expertise to fix.  There is an outfit in Canada that specializes in the repair of the SL-10  and I may end up having to ship it there but I was hoping that anyone on this forum may have some suggestions/recommendations of what the underlying problem may be.  Thank you, claviles