Ken...
if you can't find the exact gasket match for the display head, try the thin tape-backed foam on a roll used to insulate window and door edges. Applied to the top first, with the sides forming the legs of a "T". Bottom optional.
I used it to seal the back of my Yanmar control panel instead of using something like silacone so that it could be removed and replaced if necessary without a mess each time. Did it last year and no sign of the previous leaking.