Remote pulls for tank drains

We have an '05 Keystone Outback 5er. The 3 tanks all have a remote pull handle to open and close the tank valves. Last time we used the 5er, the black tank handle pulled out normally to drain the tank but would not push back in. The whole cable assembly felt like it was buckling and pushing sideways (if that makes any sense) instead of closing the valve. I pulled down some of the panel covering the belly and as I suspected the cable was pushing sideways. I could reach in and hold the cable while my wife pushed the handle and it would close the valve. This one takes about the same amount of pressure to operate as the other two, so I don't think the issue is the valve. Is there anyway to secure these cables so they won't bend? There doesn't appear to be anything to secure it to as it runs along the bottom of the black tank.