In my first floor guest bathroom I'm on my second Briggs Vacuity that wont flush. The first one had no problems for about 5 years then started to where nothing would go down, so when I updated the master bathroom I moved that working Briggs Vacuity to the first floor guest bathroom and not long later it started doing the same thing. It seem strange to me 2 have do units having the same problem in the same location. Could it be a problem with the plumbing, may be the slope is not enough and a build up in the pipes is causing back pressure. Open to thoughts on what the problem might be.