A couple of weeks ago, I noticed the spa was emptying out. My pool guy said it was the check valve (which had been replaced last year). I ordered one from Amazon but by the time it arrived, the spa stays filled and the spa runs as well as its waterfall when the pool pump is on. The pool cleaner isn't moving around. Couldn't get the heater to work either. Are these problems all connected somehow? I can replace the check valve but don't know where to start for the rest.