You should have some, maybe not much. A cyl with zilch will indicate a stuck valve.
Pot NO MORE THAN a teaspoon of light oil in the cyl that is showing low comp. If it increases, most likely its cumbed up rings than should loosen up with running.
Stuck valves; get some Marvel Mystry Oil (MMO) into the cyl. let soak for a few days, turn engine over WITHOUT spark plug in. replace spark plug turn over by hand. DON"T force the engine to turn if it feels stuck, remove plug and see if there is too much oil in cyl.
If the valves still stuck, remove intake and work valves from the inside.

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