What the thread found

• A junction box with out-of-tolerance conical pins can cause a sled to fail to return to its original balanced position after tilting.
• Flex in the mating surfaces between donkey box and junction box, measured at up to 56 thousandths of an inch, can prevent proper return to static balance when the sled is returned upright.
• The three-point conical pin mounting design is prone to imbalance if any pin rounds out or seats differently than the others, creating a three-legged stool effect.
• Switching from a three-pin conical mount to a four-pin design on a hybrid Pro/XCS mount improved forward and backward balance restoration.
• Carbon fiber post winding construction can affect overall rig rigidity and may contribute to balance issues.
• Junction box service from the manufacturer should be considered if balance problems persist after other component testing.

Depends on

• The issue was specific to one user's setup with particular serial numbers and component combinations.
• No confirmation provided on whether newer Cine Live J Box models address the original tolerance or flex problems.
• The solution involved custom machining of a mount rather than standard components.
• Similar symptoms were reported with a different sled model but root cause was not confirmed before the thread discussion ended.
• Flex of 56 thousandths of an inch may or may not be within normal Pro manufacturing specifications.

Parts

Top Stage, Monitor Bracket, Donkey Box

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