Bicycle Mechanics - Index problem - loose downtube shifter

I have some 7 speed downtube shifters that I'm having issues with. Basically, during index adjustment they shift perfectly from smaller cogs up through the larger cogs, but when going from the largest cog back down, there is a bit of extra movement in the shift lever on the plastic boss cover that screws up the index adjustment.

They're in friction mode now because of that.

They seem to be screwed on the boss pretty tight - is it just a case of worn out shifter? Or do I have the incorrect pieces that have "slop" in them? I think the plastic "mount" pieces that go on the boss first actually came with different shifters....but all were shimano and the shifters seem to fit on them ok otherwise.

Thanks - weird problem.

First thing to check is the length of the screw. A common problem back in the day was a bit of braze at the bottom, or an overly long screw that bottomed out without fully tightening the system.

Remove the lever and thread in the screw and make sure it goes in far enough for the head to touch the top of the boss. If not, tap the boss deeper, or grind a bit off the end of the screw.

Will do!

Thanks,