bobcat 331 bucket cyl bleeding off

Just bought a 2007 331 bobcat excavator with 400hrs. Nice machine super clean. While hoisting a heavy generator with a chain hung on the bucket death we noticed it is slowly bleeding off and bucket is lowering with some weight on it, also had problem with dropping some logs while moving them same thing happening, not super fast bleed off but it is lightening up.

what to do how to fix?

thanks