This helps if for sure we have the right series. I can only find the vacuum breaker valve that looks like that on the older 910. The 510''s are different but the gromment maybe not.
But I found this. See page 3
That item 3, 1/2" grommet shows up on a lot of the toilets
If by chance that 1/2" grommet PN 385311164 is what you need, then (Note: I never bought from these folks, it is just a web hit)
1/2" Sealing Grommet
I went to the PPL site that has diagrams and part numbers. once you have a part number the hunt is easier.
RV Toilet Repair Parts Online Catalog - PPL Motor Homes
Then go to on line catalog, select toilets then sealand and then go to the hundreds of models...
Then if you click "show diagram", it brings up the diagram.
If you can find the right parts guy, they can sort out of the washer I linked will work or not. I have bought from PPL and have had a good experience. If you or they can find the PN, I know they can order most anything.
Hope this helps
PS What is the PN of the new valve you bought and where did you get it?
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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