Help removing fuel sender unit 94 FrankenJetta

[williamtaygan]

1994 1.6Td Jetta.  Gas>Diesel conversion.  So I've got what appears to be a gas fuel tank.  

Last winter I had massive air bubbles and fuel clogging somewhere before the fuel filter.  Fixed itself above freezing.

I'm guessing that there's sludge in the tank. I'd like to clean it out without dropping the tank.

I've got the fuel sender unit exposed and can spin the ring around but can't pry it off.

There's 3 ridges that are flush with the outside of the ring.  I tried lining one of those up with the little arrow on the sending unit, but it doesn't budge.  Can any of these 3 ridges line up, or only one?  I can't spin the ring all the way around, so I can only get at one of the flush ridges.  Maybe I'm completely off.

Help!

[williamtaygan]

It's not what it says in Bentley.  Instead of lining up the arrows and prying the ring off, it unscrews.  Cleaned out the tank in the vehicle with some rags and poured isopropyl over the pickup screen and it ran fine through the -25F last winter.