Can you lower the lift arm all the down so that they are both lower than the pins? That way the only one you have to worry about is the one you can't manually lower. Lower the lift arms all the way down and back under the pins then lift your arms, the one that gives you trouble should latch first and then the other one will come up and latch. Since you are not trying to align both sides at the same time it should help. Hope I am not confusing you more.
Vicky
Vicky