Bit can not move in one place


This very short video shows the problem:

The bit can not move completely due to interaction with the connector between the top and bottom mechanisms on the back.

Have I assembled something incorrectly, or is this a common problem? It is not a major issue, since all other places work, but since there is a puzzle with a bit in that position, I thought that it should work.


Did you try swapping bits around to see if it is only that specific bit, or if it is genuinely the position? If it is the position, then check to see how tight to the board the connecting rod it; there should be a lot of give, but some connecting rods appear to be a little bent when they arrive. Swapping the rod round, so it bows out from the rear of the board might prevent that rubbing. If it is the specific bit, then check to see if it is rough on the reverse, and polish it gently.

Hope that helps
P.S. it could also be far simpler, and that your base is not level, as constant back and forth slows the ball down, and if the board isn’t completely level then there may not be enough momentum for the ball to escape.


It is not that particular bit piece and the base is level etc.

From looking at the back, it is pretty clear what is going on. I think I’ll just have to bend the connecting rod a little. (or just not use a bit in that position)


The connecting rods should be straight ideally, so bending against existing warping might be your solution

#5 should show clearance between the bit part and the connecting rod. shows that the connecting rod definitely could impede the rear pin of a part; in fact this is true on both sides, as the board is symmetrical.


Yeah, there’s a little warp in the board. They did their best to get rid of it during production, but some boards still have just a little too much warp. Like DoctorMikeReddy suggested, the best solution is to take the connector off, bend it a little, and stick it back on.

Connectors touching back of board and blocking holes

Thanks both of you. It is not a big deal.


For those who have access to a 3D printer, I’ve designed a spacer that clips on to the connector and gives it enough clearance to avoid the pegs. I pasted the link to the other thread on this issue: