Chainsaw is excessively vibrating when in use.

Has the chain been properly tensioned?
Improperly tensioned chains can lead to excessive vibrations. Make sure the chain is properly tensioned; you can use the knob on the side of the chainsaw. A loose chain can increase vibration levels.

What application is the tool being used for?
The thicker the wood the more vibrations will go through the unit. View the Ryobi product page to check how thick your unit can cut.