I have a bell jar whole house filter at home for the main house. I installed it in 1988 and use it to this day. Back in those days the spanner wrenches were made of stamped steel. I position the steel wrench at the top and with one gentle swing of a 2 pound sledge hammer, the thing is loose.
When installing the bell jar with a new sediment filter, I clean the black "O" ring and re-apply a thin film of Petroleum jelly on it.
I searched the web and found steel spanner wrenches sold
HERE. Mine looks nearly identical to this one.
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