If it's an original Gemmer I type model A steering gear the the question would have been better asked on the model A side of the forum. The model A gear assembly doesn't have seals like the later Gemmer II. Ford called out 600W steam cylinder oil for the model As but an SAE 140 gear lube or John Deer Corn header grease may stay in there better.
A person needs to identify whether the lube is coming out around the light switch or around the sector shaft. If it's both and the steering is sloppy then an overhaul of the unit may be in order.