Jackhammer wont hammer

A complete service kit is neccesary its pointless only to change oil, including hardened o-rings and gaskets and oil seals etc. have had their working hours. it all rests on a marketing technical calculation where no user is slicing.
look for your model and a spare parts servicekit and if the neccesary tools are present you can do it on your own. the front second hammer (stroke bolt) must be air-tight the heavy battle piece must be pulled up by vacuum by the stroke cylinder and worn rings on it and everywhere and bad seals will not succeed