NattyBumpo

I recently rebuilt the rear shifter on my Campy Record 10-sp, including replacing the thumb button return spring, the finger shift lever return spring, the G-springs and their carrier, and the index gear. After a few hundred break-in miles, it shifted slicker than owl snot for about a month. Then it began being fussy about down-shifts, shifts to the larger cogs, most commonly when it was at the extreme end of the cluster (12/11-t). It felt as if the finger shift lever wasn't engaging the detents, but I could wiggle the lever or push it inboard at different angles other than the usual perpendicular, and sometimes push it outboard, and usually I could get it to resume engaging and down-shifting.

I thought to remove the shifter body from the handlebar to troubleshoot the problem but when I removed the shifter cable (which was a new OE Campy cable when installed six months ago), I found one strand in the shifter cable had snapped inside the shifter body, near the cable nipple. Because that unwinding wire would have coiled and gathered up inside the shifter body, possibly bunching up to resist the cable being pulled, I concluded that that likely was the problem. So I reinstalled the most recent old cable, which was still serviceable and only replaced on general principles.

Except that didn't fix anything. The finger shift lever still swings like it isn't engaging the the index gear. With the bike on a work stand I'm basically wiggling the lever in every direction trying to effect some sort of change, or feel something that will help me diagnose the cause. It sometimes clicks when I push the lever outboard, which sometimes but not always is an indication that it will "catch" when pushed in the proper (inboard) direction. Otherwise, I am baffled.

So now I figure the next step is to disassemble the shifter to see if I can determine what's gone wrong. But before I do that, I wanted to front-load my search by posting here to ask for suggestions what to look for. I rebuilt an 8-sp Ergo shifter some years ago but this was my first attempt rebuilding the 10-sp, so I don't have a lot of experience at this.

TIA for your help.

FBinNY 

The most common reason that the finger lever doesn't engage on rebuilt ergos is that the small ratchet cam it engages is backward (upside down).

Then th finger lever pawl basically freewheels over the ratchet.

However, if that's your problem, I can't imagine that it would have worked for a month. All I can suggest is that you take it off the bike, and watch the action as you move the finger lever and see of you can observe why it doesn't engage.

FYI, the way it's supposed to work, is that when you move the lever, it's supposed to bend on it's pivot so it engages the cam, then drives it around. Maybe there's rust on the small pivot so it's rotating without bending and engaging.

Andrew R Stewart 

I've installed the cam (as Francis calls it) back wards as well as have had the thump lever pivot rust up and got much the same problems. +1 for his advise. I'd take it all apart and REALLY look at what's going on with each step. Andy.

FBinNY 

Before you take it apart, OBSERVE what's happening. If the finger lever pivot is binding, that can sometimes be fixed with some oil and massage.

NattyBumpo

EUREKA! The central pivot fixing bolt -- which holds the whole contraption together from the rear -- had backed out a turn or two. I noted it was loose after removing the plug from the shifter body, which saved me from having to entirely disassemble the beast. I snugged it down and put the whole enchilada back together and now it unfailingly shifts crisply and flawlessly.

Before I removed the assembly from the handlebar, I thought to turn the bike upside down to follow the majority advice and OBSERVE what was happening. Once I had it inverted, I could see the both the front and rear gears were rocking in lock with the movement of the finger shift lever. And at that moment I knew it wasn't a problem with the shift lever engaging its toothed wheel.

This is not a problem I hear reported very often, which would lead me to believe this probably was my screw-up (maybe I didn't properly snug it down). Regardless, it if happens again, is there any reason I shouldn't put it back together with a drop of blue Loctite?

Drew Eckhardt 

That seems sensible.

Campagnolo engineers worried about the right shifter bolt backing out because pointy-hood levers use a left-handed thread there.

Kimmo 

Yeah, that brings up echoes of a couple of scary moments...

BITD (mid-90s), my first big spend on bits (if you don't count $200 on a set of 600-hubbed DB-spoked tubulars a few years earlier) was to Shimergo my 7s weapon: $280 on a pair of Veloce Ergos and another $140 on a Veloce RD... sheesh, my eyes still water at the cost 20 years later. Anyway, before long I had to see their guts, and discovering the left-hand thread was a vexing process... IIRC the right shifter was the first one I tried, so I had no idea how tight the bolt would be, within the limitations of a 5mm hex interface... and of course, after making it pretty damn tight, you have cause to wonder whether you're really going the right way when you try changing direction... harrowing stuff.

...And cue the entire process in reverse 20 years later upon receiving my 9s Mirage Ergos

Which BTW, were $170 slightly used but delivered from Germany, and ~20g lighter than the ST-6500s they replaced... another $50 on a ShiftMate, plus locking out the spring carrier float = Shimergo win once more