Excellent model - thank you. I have enjoyed making it.
A couple of niggles were that my Uno board did not fit properly, I had to file the corners from the black coax connector before the board would fit in the correct location; and I had to enlarge the countersinks in the L2 Drive gear, as my M2 screws were standing proud of the surface with the part as printed.
I used silver steel for the shafts and had no problem with the fit of the bearings.
I took a lot of trouble assembling the L1 components to ensure that there was a good, even tick with no binding of the fork and escape wheel. I had to file the fork and escape wheel shaft slightly to achieve this. After that assembly was straightforward thanks to the accuracy of the parts and the instructions.
Prusa and Ziro PLA