Problem with speedpassion 10.5R

[Appie53]

Dear Guy's, bought this used speedpassion 10.5R sensered motor! When testing I thought or my diff did slip or my clutch did slip.
I hear a somewhat high tone sound and my Ansmann does'nt move, giving a small amount throttle it will move. Trying other motors everithing works like a blast, no slip sound atall.
So could this be the issue, Iám using a none sensered esc on sensered motors!
Did older or some brushless motors have starting problems?
Thanks for your support!