Hello to check the gear oil you have to find a plug on the side of the lower unit it should say fill by the plug remove the plug and the oil should be up to the hole it is easyer if you have to ad oil if you remove the drain plug first and put the tip of plastic tube gear lube in drain hole and then remove the fill plug and squeeze tube of oil till it comes out of fill hole then put back fill plug fast then remove oil tube and put back the drain plug fast not much should come out as the holes are small and the oil is thick good luck PS do this over a pan or something rags?