Disassemble and inspect your steer cylinders. If in good shape, reseal. Like others said, more than likely you have a cylinder coming apart. Once you find the problem component, a thorough cleaning of the hydraulic system is necessary to remove contamination hiding in lines, cylinders and valves. This could mean three sessions of clean oil in the tank. New filter each time. Run the machine stationary at moderate throttle. Hold cylinders at full stroke to full system pressure for 20-30 seconds until the hydraulic tank is 160 degrees. Cycle cylinders (all of them) many times while heating to flush particles around. Drop oil, filter and repeat. When you have the oil tank filter cover off, place several magnets within reach on the tank floor. Clean each magnet every time the filter is replaced. Leave magnets in there once done. Flushing hydraulic systems on any piece of equipment after a failure is very important. Cat has specific procedures for their equipment. Cutting corners will short you in the end. Adding a drain valve to your hydraulic tank will make life much nicer. I added a hose barb to the valve so I can slide a hose on to minimize the mess. I have a pic somewhere I can't find at the moment. I used a -16 street 45 screwed into the tank. Then a -16 hex nipple. Then a -16 quarter turn valve. Lastly a -16 x -12 hose barb. I take the handle off when not draining the tank. A plastic cap over the end of the hose barb. If you need a replacement steer cylinder, a salvage one from a TS14C-D should be the same.