Super easy Fix.
1) Remove the knobs, and grommets under them.
2) Use a Phillips screwdriver to remove 3 screws per side.
3) The top slides off, but mine was a bit sticky so I had to use a flathead screwdriver to get it started.
4) New unit slopped right on with no issue, I put all the screws back in, then dropped it into the hole.
5) Replace grommets, then knobs,
Done in about 15 minutes tops.
NOTE: The unit has a bit of weight to it, so get some to help balance it as you take the screws out, or as I did, get a couple of wood boards (longer than the unit is wide) to put under the unit so you can get to the screws.