JLG Boom Lift hydraulic "slack"

I was using the 600A yesterday. Drove it to the worksite about 1/2 mile. Then, I rose the main boom, and telescoped the fly boom almost to full extension.

The lowest tower main Boom Assembly then rocked forward causing the whole upper section to drop suddenly.
Thankfully I was secured in the basket and had a hand on the cage.

I then retracted the fly boom, which caused the balance to change and the Boom Assy then rocked back to lowered position which was another catapult ride in the...

JLG Boom Lift hydraulic "slack"

JLG Boom Lift hydraulic "slack"