The machine, deployed at the European Marine Energy Centre at Stromness, Orkney, has achieved more than 20,000 hours in operation.
The Edinburgh business said it is now aiming to improve the reliability of the Oyster with a view to making more sustained power generation later this year.
That will include the installation of enhanced cylinders as well as upgrades to controls.
Chief executive Martin McAdam said: "The cylinder removal operation went like clockwork. Last year it took seven operational days to prepare and remove a single cylinder. This month we removed the first module in under four days and the second one in three days.
"To achieve this, our team learned the lessons of last year, changed the procedure, modified equipment and worked with local supplier Leask Marine to improve the operation."
Mr McAdam said the testing of the Oyster in all weather conditions was providing useful data.