| It's certainly possible. The hoses could be backwards as well. The difference between a slide trigger and a hinge trigger is that one pulls the timing rod and the other pushes it so the hoses are reversed between the two types. If that's all that is wrong though, the marker should cycle it should just be backwards (ie pulling the trigger makes the block go forward and releasing it makes it come back).
If it's sticking back even when you're pulling the trigger, then it's probably just that you've adjusted the collar on the timing rod past the point where it's able to throw the 4-way to the other position. You can try turning it in 1/4 turn increments until you get it to work properly. The other thing is that if the LPR pressure is too high, it can make the 4-way very sticky and it won't want to switch very well.
I hope some of that helps. Troubleshooting a cocker, especially a new (to you) one involves quite a bit of process of elimination.
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