leak check
Tell him do a temp install on everything and see if it holds pressure. if it doesn't better to fix it sooner than later. in order to find a leak mix some water with DAWN dishwashing liquid in a spray bottle and while keeping about 3 psi in the tank spray the outside of tank along seams and fasteners to see where the leak is. Only a little soap is needed and don't overpressureize because with too much pressure the air will blow the bubbles away from the solution and you will never see bubbles. If he can get to it, scrap sealant and reseal with PR 1826 sealant (B 1/4 (15 min cure time or B 1/2 (30 minute cure time) then after it cure checks good repressurize. If in an impossible spot and a small class A leak (really small lose of pressure) you can use double bubble epoxy and apply to outside of tank for a temporary repair, but you won't find leak again. lol
My job is Aircraft Fuel Systems Repair BTW.