Move component weirdness in assembly

Hello,

I have an assembly that is demonstrating some interesting behavior when it comes to moving a part.  An identical part moves freely.  A review of the mates on each has not helped me to understand this behavior.  Given the following photo:

I find that I can freely move the slide circled in blue.  However, the one circled in red will move momentarily and then stop.  I can "grab" it again and move it a bit more, but then it will once again stop responding to mouse movement.  Seems to be time related - that is, if I move fast, I can move farther, but if I move slowly, then not very far before it locks up.

The part in red is the part marked "6823_linear bearing<1>" in the FMDT.  The part marked in blue is "6823_linear_bearing<6>" in the FMDT.  The others are fully defined.

Thanks in advance,

SolidworksAssemblies