c351 jam only when duplex

[mrfuser]

Simplex is fine. Only jams when it pulls it back in to do second
side.

Any thoughts?

Thanks all

Kelly

[Spratt]

I've come across a similar sounding problem where the exit drive lever breaks thus the duplex drive not engaging.
I have attached an image and circled the part which is found above the fuser on the rear side i hope this helps.
16321