Spring tension and pedal height same but double bass unbalanced?

So I recently bought a Gibraltar 6600 Double Bass pedal. I've been constantly trying to balance both pedals out, but it just won't happen. It seems that somehow the left pedal always sways back and forth for way less than the right pedal. And the spring tension is exactly the same for both of them. So is the pedal height. When I pull the beaters back with the drumstick and let them go, they start swaying at what looks to be the same speed, but shortly after they're off balance, and the left beater stops a lot earlier than the right beater. I feel like it has to do something with the friction on the left pedal being problematic. I did hear that the left pedal is always gonna swing back and forth for a little less than the right pedal because of the connection rod, but we're not talking "little less" here. What do you think is the problem?