Yeah, I have seen that happen before. Never really fun trying to find the ball bearings so that you don't slip on them later on (or worse case in which they fell into another server and cause a short).
I would say time for a new rack mount kit or rail. Also, the difference between the kits really only matters when 2 conditions are met.
1) You have a deeper server chassis that is longer than 24 inches
And
2) You prefer to work on your server while it has been extended out of the rack on its rail kit.
Personally I never work on a server that is still in a rack while extended out due to possibly tipping the rack (you never know if someone installed the anti tip bracket and it is properly secured, so it is best to treat it as though it is not there). So I always remove a rack mounted server from the rack and take it to a table to work on it. But that is just me and my work experience dealing with larger server rooms and multiple people maintaining equipment, but I just find it easier in many situations to do that (I think the only exception has been with servers that are completely toolless and fully hot swap for many components and I am simply replacing a hot swap fan or other component, but super micro cases typically have a dozen or more screws that you have to deal with to take off the top panel, and that is a task better performed on a work table, not hanging out the front of a rack).