Originally Posted by DrRobert

Here's the deal:

Shimano 105 shifters and derailleurs. Bike is app 10 years old.

Several months ago the rear shifter handle started flopping when shifting down like there is no engagement at all. Shifts up (higher gears) fine.

So I figured the cable is hanging up, check my cables and found a little bit of corrosion at the top of the cable tube. Replaced the cable and housing worked for a while now its doing it again.

If I grab the cable where it goes down the tube and give it a little tug that kind of resets everything.

Before I remove cable from housing and rinse everything out, any ideas of other things I can look for?

When I put the bike in the stand it shifts fine this only happens "under load".