How is the moisture? Is there alot of green straws in it? I asume that straw is long since it's heavy wheat.
The tension on the feederhouse clutch seem to be ok since you got the banging noise before it stops, but check it anyway.
Is the chain set in hi position. You might need that for the big straw flow.
Is it wrapping on the drums?
Try to open the concaves a bit and raise rotorspeed, it might be building up in the feederhouse because the rotor cant drag it in, When I think of it I've had that problem a while back.
i don't know wideopen but we had the same sort of problem last year in wheat and we ended up loosening the feeder chain only a very little bit and it stopped. what we think was happening was the load would come on the chain and in the high pos it would leave the idler bar on the top and if the load came of abit the chain would bump down making the clanging sound. don't know but it worked for us.