Welcome to the SeeMeCNC Community

Hello. installing them I was a little confused the direction of the eye. but I think it does not matter(now i have gray plastic on right side and black on left side). have a small question regarding tightening gray sleeves. if there is insufficient tighten that one of the wheels with a black sleeve is not cool, but if you pull up a little not so fast moving all Cheapskate Carriage. Also there is a clearly felt movement steps. Is this normal?
Some photos:
http://cs618717.vk.me/v618717033/ae0b/qO846A3Fgv4.jpg
http://cs618717.vk.me/v618717033/ae14/jD85c8h_cDU.jpg

Sorry if I misinterpret the question..

All wheels should touch the aluminium and each wheel should turn when the carriage is moved up and down.

If you're finding that one wheel is not touching then perhaps one of the gray cams is too tight causing the carriage to be skewed and keeping a black wheel from touching....

Again sorry if this isn't what you were asking.