I have a problem with the hydrastat. it turns with the engine running but does not engage. This has sat for two or three years and not moved, is it possible that the balls are froze or dirt settled into the valves and locking it up?? Could a person just change oil,( what kind and wgt.?) and perhaps run it for awhile on blocks and get it to operate? Rather has me bumfuzzeld. Thanks for any and all help.