You're on to it Jude! Anytime weight is added to a lever on the "load line" end,
it slows acceleration, but on the other side of the rocker anchor, fulcrum, it slows, acceleration
too,
allowing the work end to move more; receive more of the energy, like a teeter-totter with
one rider, and the dart on the opposite seat. The only
advantage, light or heavy dart, has to be a weight below the fulcrum. This weight also
causes the bottom to go backward less, causing the top, working end, to travel farther
-- slightly longer stroke. That is, the fulcrum will move forward more than it would without
the weight.