Gentleman the lever that is missing is the safety lever not the cocking indicator. This gun does not have a cocking indicator.

The large round engraved knob on the side is where a cocking indicator would be if the gun had one. That knob is the end of the tumbler spindle. That spindle usually has the indicator on it.

No the missing parts appear to be the safety lever, safety lever detente and safety lever spring.

Is the safety spindle or tumbler present in the action? These are the two additional parts to this style safety system. I can not tell from the pictures if those parts are missing or not.

I didn't get a chance to look for the Greener .22's that I have, Holidays did get in the way.

All the missing parts would be fairly easy to fabricate, except the safety tumbler. That one would take a good deal of fitting to get right. The arm has to set at the right arc and length and face to correctly intercept the safety arm from sear tumbler.

This safety had two functions, safety and loader/deloader.

Most aren't aware of the loading/deloading function

In the Martini, if properly adjusted and not worn, lever openthe top of the breech block will slight block the chamber. In order to load a round, either depress the lever to pull the block down or snap the round into the action. To Unload depress the lever.

With this safety system to load open the actio and move the lever to depress the block to let the round drop in the chamber. Move the lever to raise the block back to block the round from falling out.

To unload open action slowly, move the lever depress the block and the round will slide out.

Here is a quicky video, I made to demonstrate this operation

https://youtu.be/IUVydUD6PO8

If the round was fired, you will need to snap the action open sharply to active the extractor and extract the empty case.

The rifle pictured is not a BSA.