Curtiss

I recently bought a used bike with 105 STI shifters. I'm not sure the left shifter is working correctly. It's a 9 speed triple, ultegra derailleurs.

The left shifter has four positions. As I understand it, it should be adjusted such that 1 is the inside position and 4 is the outside position, 2 and 3 should be slightly inside and slightly outside of the middle chaingring respectively.

Problem is, when I'm in 3 (middle, outside) and want to trim to 2 (middle, inside), there is no single click click available. I can only release all the way to 1. I'm pretty confident that cable tension and both stops are set correctly. All four positions work nicely on the way up the chaingrings.

Question is, should I be able to click from 3 to 2 when properly adjusted? That is, is the shifter broken?

I've tried to overcome this problem by setting 1 and 2 as inside/outside positions on the inside chain-ring, 3 in the middle, and 4 on the big chainring. This way a shift from 3 to 1 puts me in the small chainring and if it's rubbing (because I'm cross-chained (which, of course, I shouldn't be)) I can just trim to 2. Unfortunately, even with the stops properly adjusted, set up this way position 4 rubs when in the smallest gear in back (rubbing on the outside of the chain). If I tighten the cable even a little, it won't shift from 4 to 3. Also, without a trim, I don't have the range I'd like in my middle chainring (this is the biggest issue).

I also read somewhere that 3 and 4 should be set up as inside/outside on the large chainring?!!? Seems people are all over the place on this. Even that doesn't work for me. Set up this way, shifting from 3 (which would be inside position, large chainring), it skips 2, jumping directly to my small chainring.

Thoughts? Again, could it be that the shifter is broken?