It suddenly started running slower until it stopped, what can I do? Janome JA 1512

It suddenly started running slower until it stopped, what can I do? Janome JA 1512 https://mans.io/question/view/27949-it-suddenly-started-running-slower-until-it-stopped-what-can-i-do-66400458168__edf27729-7ab6-42e5-904a-639e226a791c