I have a 3450 SFF and trying to install M.2 drives in it.

There are 3 slots for this 2 of the 3 have the barrel standoff to screw down a M.2 the 3rd does not.

Does anyone know where I can get that part from? Support has been no help and there fix as of now is to replace the motherboard. 

I purchased a standoff set from amazon but the screw thread was too small to accept into the motherboard/chassis