For the smaller holes, you can use great stuff-foam insulation. Comes in a small can, buy at hardware or big box stores. Make sure you know where all the holes are as if you quit using the stuff, what is left sets up and is no good. If you have quite a bit to foam, they sell a gun that uses bigger cans. The gun costs less than $50 and the cans are 10 to 12bucks, but the contents are equal to 10- 12 of the small cans. Also they can be left attached to the gun for quite some time before it sets up. Overnite is no problem, and I have left mine in the truck for weeks and it still works. I do clean everything on the outside with acetone, tho. Good luck with it, Arne.