Singer 746/760/784/786=2500 WAB/RAB22-12 motor insert/spacer,bushing,604229-001A

 
This is a round spacer and not an elliptical, it may be a little different to the one in your machine but it wiil work.
 
METAL-CAB-8-N60PHIL-1-2019....NOW-N90PHIL=001122