Starter does not spin

Moin, unfortunately, my Kreidler Florett 2.1 RS 50 starts with the E-starter only very sporadically and now apparently no longer at all. Sometimes it turns after felt 50 attempts and then starts immediately. I checked the following: – Battery has enough power – Relay switches – Current arrives at the bottom of the starter – Roller starts with Kickstarter without problems Now the strange thing… if the starter is installed, just click the relay, but the starter does not turn. n expand and directly with 12V supply he turns. I am grateful for every tip!