Assuming you havent installed
pickup rings on your 7620, they are direct mounted, and dont have springs. So the 2 strips of...black mush...are the only things which hold up both sides of the pickup. When I say black mush I hope you know what I mean. Its...foamy...Anyway...Those are probably just set at the lower height you had the pickup and wont expand to hold the pickup at the higher height...So...solutions??
Well...You could get new foamy things. Anything will do. Some even use a block of wood cut to fit the cavity but allow the screws down into the body so the pickup can be fixed at a certain position. You might want to try this method as it also might sound better having wood inbetween the bottom of the pickup and the actual body. It would also be a lot more stable. But new foams would do the trick too. Thats a lot less time consuming. Either way its up to you.