My 300 U is now showing complete failure of hydraulic system; i.e. no movement of cylinder what so ever. Fluid level is FULL, operating handle is engaging the shaft on the spoiler box. Nothing is happening. I had trouble last winter. After posting here, I drained fluid, heated over night, and all worked fine. Is it possible that the screen in tank is sucked so flat that no fluid at all can get through? What else could be wrong? I have noticed that every once in awhile there is a kind of funny sound coming from the hydraulic pump. It is very brief and may slow the engine just enough to notice. Could my pump be shot? If pump shot, can it be rebuilt for less than a new one? Where to do this? thanks all