Do you have a compression tester? If not, undo the two 8mm nuts that hold the exhaust on and remove it- look inside the exhaust port and inspect the condition of the piston as you slowly pull on the recoil rope. If it appears to be scored, then you have no compresttion and will need at leas a new piston and rings and quite possibly a new barrel- in which case it would be beyond economical repair.
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