Tim seems to have identified the problem...
And told you how to cure it. The exploded diagram for the Newport is here: http://www.wilcoxcrittenden.com/sanitation/electric/newport.asp?bid=Scroll to the bottom of the page to get to the parts list and diagragm...it'll come up in a popup window...maximize it, then click on the drawing itself to enlarge it further. Part # 28 on the diagram is a macerator blade, but there is no part #28 on the parts list. Since Thetford-Norcold bought W-C, getting to anyone who's actually at W-C and can offer any tech support has become d'd near impossible for anyone who doesn't have the direct #...which I just happen to have: 401 846-1679The people at W-C have admitted there have been a lot of problems with the Newport...even they don't recommend it. I'm not sure whether they're due to a design problem or quality control issues during mfr'g, but if they can't recommend it, I don't. So go to the link Tim gave you...his step by step instructions and photos are pretty complete...and also give W-C a call at the # above to ask 'em about the missing macerator blade (part #28 on the drawing) and how to install it correctly. Tim, I'd like to have everything in the link you provided for my files..not a bookmark--archived posts on sites tend to disappear for various reasons. Any chance you could put it into a document and email it to me as attachment?