[tunabreath]

I personally think that if you're going through the trouble to put in a 'proper' moundless SCS install, you'd be even better off with an R-hop.

I did a moundless SCS install recently, and while it was quite accurate, I couldn't get enough hop to toss 0.30g+ without encountering jamming and extremely accelerated wear on the hop up bucking/sleeve.
For reference, the way I solved the problem you are having right now was to use a dab of hot glue as flack suggested to keep the SCS orientation fixed, and also to super glue a thin layer of plastic on the inside of the opening in the hop arm that the adjustment cams against, shimming the whole arm adjustment range lower.
The setup eventually died by stripping a piston due to a hard jam.

*for reference, I was using a Guarder Clear bucking. That might have exacerbated some of the problems I was having; they're pretty well known for not being the most durable things around.

I'm definitely just going straight to R-hops in the future. They're far less susceptible to these problems and almost impossible to wear out, as well as offering similar (arguably superior) accuracy potential.
-bonus, the work you put into shaving the mound off is equally applied to an R-hop, which also uses a moundless bucking.