Here is what the OM says:
View attachment 7299772
J1 is consistent with how I interpret the block diagram.
I think the wording is inaccurate/misleading for J2. Per the block diagram, when engaged in the Post position, the second DI is essentially a duplicate of the other output. It's not "post Clean channel
only." It's post whatever you have selected.
If you have stereo engaged and are using a stereo effects processor, it's post whatever you have selected processed through the right channel of the effects unit. You have mono going into the effects processor and stereo coming back into the return.
It's possible the block diagram is wrong or incomplete. It's also possible I am misreading it.