That's a serious problem. Wear gloves, mask and goggles, dispose of them immediately after. You can take the batteries themselves to your local city hazardous waste operation (although ours is closed right now for Covid19) but be sure and label them and put them in heavy, clear bags so that whoever works there realizes they are different. You can buy a 'mercury cleanup kit' from industrial or lab safety supply warehouses, but they are expensive. They will contain either sulfur or iron-zinc powder that will react with the mercury to form a much less toxic compound.
Frankly, as much as I like fixing up old equipment, you might want to pass on that project. If you do just put the whole thing in a clear bag and explain what you've got to the hazardous waste people. That's a LOT of mercury in there, many thousands of times as much as in the old alkaline cells.