I made a video in the Software Questions area about a difficulty that I was having with rotation, and in that video I showed that I am also having trouble with my nozzle holder. Michael was very kind and he emailed me about the problem very quickly asking for more information. So, I'm making a new post here in the Hardware Questions area with two videos. The first video shows the problem (which I have always had with the machine ever since I got it), and the second video shows my temporary solution to the problem. I think that a permanent solution is to have a new slide mechanism for my machine, but SmallSMT would need to send me a new slider, which I would be very grateful for!

Problem video: https://youtu.be/ca3ajDtvoLQ

Solution video: https://youtu.be/6ty426lsqtc

Hi Michael,
Thank you very much for your reply. Yes, I did try to use WD40 on it before I made those videos for you. I also looked to see if there was any dirt, but it did not look like the guide bar was dirty. The WD40 helped a little bit, but the video that I made was after applying the WD40. Also, I did make sure to use the factory calibration files from the CD. I will take care not to lose the ball bearings when I install the new slider that Sunny is sending. I can make another video of the installation if it would help you.
Thank you again for your support!

Hi Michael and Sunny,
I'm making a lot of videos for you lately! I thought that I would make a video for you showing the difference between the factory calibration file (which I used from the beginning), and my own calibration file (which I made after I realized that the factory calibration file was causing the nozzles to not get picked up). In the first video, I use the factory calibration file, and the nozzles fail to get picked up. Even when the nozzles do get picked up, I get E3 errors because the heads push down a little too far on the nozzles (I can see that the heads have a Z error after picking up a nozzle -- the heads are nicely aligned vertically before picking a nozzle, and poorly aligned vertically after picking a nozzle. If I pick with the other head, the misalignment changes direction, but is about the same magnitude). In the second video, I show the nozzles getting picked up nicely after I carefully calibrated all heads (X,Y,Z,X_Exit,Y_Exit,Z_Exit).
Factory config_nozzle.fig with failures:
https://youtu.be/-rFpeY-fqdo
Custom config_nozzle.fig without failures:
https://youtu.be/kYH7xXs8UuE

I've made good progress today. Thank you for your support!