I WISH that Forest River had a better manual that, among others, described the use of the flush. As a rank 'Newbie' I had NO IDEA how useful it is. 

I loaded the black tank with ice, detergent and Calgon water softener and spent some time on a couple of nice West Virginia roads (Twisty, steep and rough) but I'm still blocked. Until it clears with repeated treatments, from now on each time I dump, I'm putting a couple of gallons of water down the toilet to mimic the effect of the flush, and a 'Johnny Chock' may be in my future.

I really wouldn't worry too much about it. As I said, I had this exact problem. Fixed it and I haven't had ANY other problems with the pod. 

Ok, I put the valve back in, facing the correct way now, with just a little crimping of the 'outflow' hose because of the changed geometry of the replaced valve position, but not so much it couldn't be pinched opened by my fingers.

So, I just turned on the water, no flow, at least by ear, and the backed up water pressure was sufficient to blow out the little screen in the entrance hole when I removed the hose (and drench me, of course). 

So I know it's still plugged.

I presume the blockage is between the outside of the trailer and the valve because I felt no vibration in the inflow or outflow hoses when I was jiggling the valve up and down to ensure that there was no crimping, and also there was no leakage anywhere, which considering my nonexistent plumbing skills, I totally expected.

Now, I really like my R-Pod but this makes me suspect that the fumble-fingered, ignorant, #$**%$# of a trainee who put in my valve also did something else to cause me this trouble. 

   ?Any suggestions as to how to trouble shoot this???

Altho the valve won't destroy if it's put in wrong, it just won't work.  http://bay172.mail.live.com/mail/ViewOfficePreview.aspx?messageid=mgRrtEsfH05RGUKAAeC8wHzg2&folderid=flinbox&attindex=0&cp=-1&attdepth=0&n=70562650

So, I bought an old-fashioned 90 degree elbow, figuring to add it and 'straighten out' the current 90 degree bend of my installation. 

My Question - It's for a regular house, metal and heavy, should I wait for a non-metallic one?? http://www.walmart.com/ip/44692995?wmlspartner=wlpa&selectedSellerId=83&adid=22222222227031995551&wl0=&wl1=g&wl2=c&wl3=61117744736&wl4=&wl5=pla&wl6=108512472776&veh=sem 

I eagerly await your responses.

Attach is a photo of the one-way valve. The picture is shot up from the floor of the shower. The valve is black. The square part of the value needs to be at the top or close to the top. 

MANY thanks to GLBCamper and funks.

I agree with GLB CAMPER on reversing the one way valve. Just take your time, very easy. After I reversed the valve on our 179 I had to remove the sprayer off the black tank and clean it. When the valve was installed wrong the flow would come up the line the wrong way and it plugged the sprayer.  I also sent water through the newly installed valve before reinstalling the sprayer.  You want to make sure when you reinstall the one way valve you keep it in the upright position. Good Luck and enjoy

I disagree. From the internet - 

" The old-time warning caveat emptor (buyer beware) no longer applies because the seller nowadays is held to a higher standard of disclosure and has responsibilities for defects which a buyer cannot see from a casual inspection."