There is no clear place to put a comment such as this, but…
The chain on my right hand drive motor came off the sprocket today with the consequence that the chain on the left hand drive motor and the sled became a pendulum slid across the work surface and struck my left knee.
My injury does not seem to be serious but could have been much worse,especially as there was a running router on the sled at the time.
I was in the way because I was at the computer set up to the left of my Maslow.
I do not know why the chain came off the sprocket. I suspect that there was enough slack on the take up side that it got pulled into the drive side. I’ve been playing with bungees, gravity and weights are looking good.
I suggest one should avoid placing one’s self in the working plane of one’s Maslow while it is running.