marauder f & t hammer stroke adjustment moves?

I was having an issue with my .177 marauder field and target with the velocity increasing over the time I have owned it, over a year. I could not lower the velocity with adjusting the hammer spring, so I looked at the hammer stroke adjustment. One of the forum members contacted Crosman for the stock settings and was told that the hammer throw is set at 12 turns out. I checked mine and it was at 4 turns out and after I moved it to 12 turns the velocity was where it was when I first got the rifle. After shooting for awhile, the velocity slowly moved up so I checked the adjustment and it was down to almost 11 turns out. Is it normal for the stroke adjustment to move over time? Also, can it be adjusted too much so that the striker pin falls out?
 
You will need to remove the hammer .... coming in from the side of the hammer ( Striker end ) is a hole that passes threw the threaded center hole.

On the other side of the center hole the side hole stops creating a small pocket. In this pocket sits a plastic / nylon piece of material that acts to create drag in rotation of center screw.

* Unscrew the stroke adjuster from the hammer, with needle or small pick dig out this bit of plastic. Now using a piece of Large weed wacker line cut it into a short section and drop it in the side hole finding letting fall to the bottom resting it in pocket. ( You want length so as screw is put back in the weedy line is crush / compressed into the pocket creating rotation resistance to the screw.



OR ... if you have VIBRA-TITE thread locker ? Apply it to threads of stroke adjuster screw, let dry and assemble.