I broke it

I was plotting the other day and all of a sudden the pen scooted off the board and hit the wall.

One of the bobbins that wind up the fishline had broken it's glue joint.
I got a new bobbin and glued it back on with JB Weld.

Then I ran a couple of calibration plots to see how well it worked.

The diagonal lines are the result of the bobbins not being centered on the motor shaft. There are lines at right angles to the left motor that I didn't fix but very few at right angles to the right motor. Comparing these to ones that I made back in March I think I did a better job of centering the bobbin this time.