ID this part that fell out of back wheel motor assembly

[miguelsnow]

Hi All,

I was assembling my new rad runner bike and when I took off that back wheel to slip the fender in, this small part fell out and have no idea where it goes -- it may be important?

Any help ID'ing this part and where it belongs -- much appreciated.

Photo attached.

Thank you

[FortunatelyTheMilk]

It's a guide for the chain, it fits into a socket on the tensioner.

[FortunatelyTheMilk]

Looks like mine fell off at some point too!

[miguelsnow]

Thank you -- !  Mystery solved.