I haven't had much in the way of problems with the OS remote needle valve. The biggest thing appears to be that the threads are a bit loose and sometimes the O ring doesn't seal too well. A tiny, two turn spring of 015 music wire that drops into the NV body and pushes the needle out a bit helps a bunch. A heavy coat of waxy, Nev'r Sieze on the threads help keep things stable too, along with a short piece of silicon fuel line over the end of the needle.
The other easy trick, turn the backplate 90 deg. to the right, when viewed from the back. This puts the needle just outboard of the exhaust stack. Grind a small relief in the boss on the muffler and the needle valve will fit just fine. If you can still get the parts, OS sold a metal bracket with a bolt-on version of the needle valve that install with no grinding. Tower may still have them. Now the fuel follows the same path it does with a conventional needle valve, down under the engine, which gets rid of all the starting and running problems. You will have to reverse the fuel spigot in the venturi too.