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What seeder did you get that is 690lbs?
The lift specs is at 24" behind the 3PH balls: Lift Capacity (24-in. behind link arms), lb. (kg)681 (309) so if the majority of the weight is further than that you can have problems. You could always ask the dealer to perform a pressure test of the hydraulic system to be sure it's up to spec also.
What seeder did you get that is 690lbs?
The lift specs is at 24" behind the 3PH balls: Lift Capacity (24-in. behind link arms), lb. (kg)681 (309) so if the majority of the weight is further than that you can have problems. You could always ask the dealer to perform a pressure test of the hydraulic system to be sure it's up to spec also.