Check your cart properly attached to the headshell.
Then make sure the arm hight is set to the right level. This will depend on your cart. Measure it and check in the Technics manuel for a table showing hights etc.
Then check the weight is set to the right level. Check cart manufacturers recomendation for this.
Anti skating is usually set to zero for DJ use. It counteracts the force pulling the arm inwards, however, when you scratch a record backwards and forwards it works against you.
Also make sure the actual tonearm is smooth by moving it into the center and back again. If it is noticably wobly or stiff then you have a problem. (this is unlikely though)
Also your needles may need replacing.
Also shit quality carts and needles skip more than good ones.
For example I used to have Numark groovetools and they jumped all the time. Now I have Ortofons they have never jumped.
Finally your records may be a little warped or a crap pressing.