take it to a trained repair technician
-------------- new answer ----------------
See the YouTube link below
No-one seem to have a diagram on the repeater but I did find this on the web. see the link below
Crosman does not own Marksman. Crosman made a Repeatairmodel and Marksman made a Repeater model. See the link below for the Marksman Repeater owners manual.
There is No C02 cartridge in the Marksman Repeater, it is spring operated
The Marksman repeater is rated at 200 FPS.
Take it to a trained repair technician to avoid possible damage. ---------------- New answer ---------------------- See the youtube video below
The Marksman 2002 Repeater is rated at 250 FPS.
There have been several models of the marksman repeater. The first one was made in 1955
18 BB according to Marksman
See the Link below for the "you tube" video for Marksman
It is rated at 200 FPS
Needs to be serviced/repaired
100