Alrighty then , let me be sure I understand what you think the problem is . If I'm understanding you , the guides that the block slides in/on are loose and sloppy . Draw a line from center of top wheel to center of bottom wheel . Let's designate this line as "X axis" . Is the front guide block rotating in this X axis ? I think this is what you mean with the purple circle and arrows in your picture ?
--
Snag
Men don't protect women because they're weak .
We protect them because they're important .
