Quoted from flx:laser + motor didn't stop when "klingon multiball" was over (only one ball left).
the laser was still on while playing the next mission, until the last remaining ball drained.
this happened twice already. sounds like a bug to me.
This happened to me as well on ball two. Laser was still going after Klingon MB ended. Didn't go out till the ball drained. Ball 2 back to normal