The front meter (seed) on my 2320 cart is airtight and rebuilt the rear (fertilizer) due to a side plate that cracked. Everything is air tight except for the back of the meter door where the hinge is. There is a little flat area on each side and then at the bottom where the manifold meets the seals it leaks between the 2 rubber Ls. Tried weather stripping and cant seem to get the meter in and door closed at all. Even without weather stripping in those spots its next to impossible to get latched. How much air loss is normal for these?