Hello, I am also making an engraving machine. I use a 1605. After I bought my screw, I processed the two shaft ends and removed the screw nut myself. Judging from your situation, it seems that it was not disassembled properly or the ball fell off during installation. Let me tell you the method I use: First, make sure that all the balls removed from the mud are not missing, and then prepare butter (prepare some diesel or kerosene if possible). Then check how many nut commutators you have. Mine has three plastic commutators, so my lead screw has three circles of balls wrapped around the top and bottom of the lead screw to install the balls:

1. Coat the ball with butter and stick it to the commutator in the screw nut. Use it as a starting point and stick it along the thread.

2. If you stick it correctly, you should be able to return to the starting position. This proves that you After gluing it correctly, be sure to leave a gap between one ball and half a ball in each circle

3. Install the remaining two circles according to the above steps

4. After installation Slowly screw the screw nut into the screw. You may have to try a few times before the balls fall out. You will succeed

5. Use diesel or kerosene to wash off the butter in the screw nut (use Other methods will work), and then drip in lubricant.

I have been testing the machine these days, and I have the opportunity to share the following experiences.