Rear derailer springs
I am either getting weak or picky. I have a friction shifter and if I adjust it so that it is fairly easy to move then the RD will pull it back into a higher gear. I have another bike with an indexing shifter and it pulls easy and then stays in gear. Probably one of the reasons index shifting is desired. It just seems to me that the springs are way to strong. Is there a way to adjust these springs? I am thinking about modifying the spring tension the hard way if there are no adjustments.
The problem is that there's not enough friction in your friction shifter. Try tightening the screw on the side of the shifter so it won't slip-
You DON'T want to weaken the derailleur springs as the shifting would suffer badly. The derailleurs rely on spring tensio to position the cages over the cogs or chainrings. You must have your shifters tight enough to avoid moving under the spring tension and if that makes them hard to move, so be it.
Sun Tour made their Powershifters with a one-way ratchet to make friction shifting easier. If you can find a set of these they will help.
I dug a little deeper and found that the biggest problem was the short length of cable and housing that goes to the derailer. I got this lubed up and almost all of the problem is now gone. I was surprised at how much friction this small length of housing was producing.