SYM Sanyang Super Duke 125, electric starter relay

Hello dear forum members, my scooter, SYM Sanyang Super Duke 125, unfortunately sometimes no longer jump on by electric starter, then has to press the kick starter. I have already checked the start switch on the handlebar, as well as the battery, both OK. Question: How do I get to the starter relay or where does it sit? What do I have to dismantle everything to get there? Have not yet dismantled a scooter? I am grateful about every tip/help.