Maybe not as big as you might think. First, the air conditioner area is not involved in the shell height issue (seals are a different question), so no need to worry about that.
Beyond that, it appears that the shell heights in the area are OK when the shells are down, but not OK when the shells are up. So I would tend to ignore whatever sets the shell heights in the "down" position and concentrate on whatever sets the shell heights in the "up" position.
This is the lift arms - the white rectangular metal tubes that swing up to vertical as the shell rises. Either the lift arm for the rear shell isn't lifting high enough, or the lift arm for the front shell is lifting too high. The adjustment for the lift arms is at the bottom of the arm, where there are four big bolts that clamp the arm to the bent end of the torsion bar. The adjustment procedure is basically to open the shells to take the pressure off the torsion bar, then loosen the four bolts, then adjust the shell height, then re-tighten the bolts.
WARNING: that description is a simplified summary! The details of the procedure have been reported in great detail here on the Forum. Remember, the shells weigh several hundred pounds, and must be supported and controlled before you loosen those bolts. Doing so is straightforward, but expect to find that timbers, a hydraulic jack, and a rubber mallet are involved.
Other Forum members have more experience in this area than I, and will join the discussion. They may disagree with my conclusions, so listen to anyone who has done it. ISTR that Commodor47 had some particularly good photos - you out there Dick? At any rate, be sure you understand it all before attempting it.
