If the haze is on the inside, the seal has been broken or the lens was not glass. At any rate, a sealed gauge is not repairable. You have to damage the bezel to remove the lens.
Depending on the construction of the bezel, I have opened up sealed guages by carefully opening up the bezel on the back side of the guage front where the bezel is crimped back over the guage housing. A small pair of diagonal cutters work for this. Re-seal with silicone and re-fold the bezel after doing the necessary cleaning or repair.
