JLG 600A main tower not dropping

When unit is cold, I can operate all controls fine. I will get in the platform and spend an hour working at height. When done, dropping down, all works with exception of lowest, main tower cylinder won't retract. It will go up but not down....I checked I have enough hydraulic fluid when all is down. Main tower after hours of sitting will go down and act normally till next time I am in the basket...

Getting tired of jumping down from height...

If it was a limit switch, I would predict...

JLG 600A main tower not dropping

JLG 600A main tower not dropping