Hello AngieArch,

Thank you for your feedback. We are sorry to hear that you have experienced an issue with the chain staying on the bar.
Chainsaw chains can come off due to multiple reasons such as worn-down bars, worn-down sprockets, and wrongly set chain tension. Please check the chain tension and condition of all parts prior to using. If anything is worn or damaged, replace parts before using again.
Replace the bar if:
• the groove is not fit with the height of the drive links (which must never touch the bottom).
• the inside of the guide bar is worn and make the chain lean to one side.
Chain Tension:
Chains should be tensioned before use. Check intermittently throughout each chore to make sure the chain is kept properly tensioned. A correctly tensioned chain should only pull away from the bar enough to fit a dime (10c) between the teeth and the bar.
*Do not tension a chain after you have finished using the tool. The hot metal expands. If the chain is tension when hot, then allow to cool. The contracting metal could potentially damage the chain, the bar and even the unit Wait until the next day for use (or at least until cooled) before tensioning.
Should you have any further questions or warranty needs, please feel speak to Greenworks Customer Care at 1-888-909-6757 (1-888-90WORKS).