I usually just put the front and rear concaves in to level, zero them. That way I could see what bar front and rear concaves are hitting on and how much. It sounds like you would have to shorten the adjusting rod at the front of the left side and then reset the stop bolts. To adjust the pinch point or what bar the concave touches the rotor on you would use the draw bolts on front and back of right hand pipe. If you do try it like I describe with the middle concave out, just make sure that rear concave doesn't slide down on right hand pipe before you clamp it down or you won't get accurate results. I would think that there are a lot of combines around that don't have the concaves leveled and or pinch point not set properly, and it definitely makes a difference on how the combine performs. Yeah it may be a bit of a pain because you still have to sort of lean over the auger bed to look in but there are worse jobs.