OK fitted the new floor, made it nice and level, one joist at the end was a bit low. However now when trying to fit the threshold bar at the door the old floor I'm meeting with is lower at one end. The expansion gap between the two is a bit wider than I'd like also. It's carpet on the old side, so I'm a bit unsure ass to the best solution and am considerinhg trying to make something to custom fit as the standrad carpet/threshold bars don't seem suitable. Any thoughts?