It works at the top of the block, and works at the bottom of the block, but it just won’t pull the cable in the middle of the block. Instead of pulling the cable the shifter just snaps across to the left as if there’s no load on it. Have these levers got a torque sensitive safety feature to stop you snapping the lever?

The cables arn’t particularly old and there doesn’t seem to be excessive friction in the system.

I’m wary about taking them apart as thy are still under warranty.

Anyone had a similair issue?

Cheers

Pretty sure there were recent issues with LH road STI units failing, and being replaced under warranty.

Sounds a bit odd as seems like you’re talking about the RH shifter whereas the common issue is the LH (front change) shifter that used to fail. The fact they work (presumably consistently) at the top and bottom but not the middle of the cassette is pretty odd to. Personally I’d get your LBS to have a look.

105 LH shifter controlling front derailleur any chance?

LH 105 units were/ are renowned for it

I guess the clue was in the title on second reading :p If it’s the LH then yeah it’s broken and needs replacing if you want get it sorted under warranty. Even if you can it might be worth getting one of the bargain ones from Merlin (assuming it’s a double not triple you have).

Yep, it’s borked! 105 in particular had this issue.

Ooops, I balls’ed that up. It’s a right hand, and its an Ultegra.

I had the same problem on some old Sora levers.
The cable was getting stuck.
I had to whip the cable outters off, clean the inners, flush the outters with WD40 and regrease them with Rock n’ Roll lube.