I had some problems w/ my Shakey Hunter set-up as well. I ended up mounting it just high enough so the launcher arm doesn't hit the shelf when it drops. Also, felt on the shelf and covering the launcher arm helps as well. I just ordered a couple "leather thongs" (I'm not making this name up, I'm not that clever) for it and will do a review when I get them installed and shoot a few dozen arrows thru it. Cabelas sells them (but doesn't call 'em "thongs") as does "Wild Outdoors" website (Jay Greggory).

Yes, my rest will be wearing a leather thong. Insert various jokes here....