If you're a bit handy, it might be a simple fix. The push rod is connected to a cable that slides in a sheathed cover. In order for the cable to slide in the sheath, the sheath must be clamped at it's start and at the end. Sounds like the clamp on the sheath is loose. If you can access the area, finding the extra movement should point to the loose clamp. If you're lucky, the clamp can simply be tightened. If not lucky, the clamp may be broken or loose and not able to be tightened. Good luck with it. If you do a Google search, you'll see how they operate.