Do you have one of these levers with the notched locking lever?
The locking pawl actually saws through the cast post after a few thousand miles and the lever no longer holds the clutch disengaged when the lever is locked. See how the casting is almost sawn all the way through?
I cut a small bit of steel and bent it to fit the cast post where the locking pawl rubs and used some JB Weld to secure it to the casting so the pawl now rubs on steel rather than soft aluminum.
Best part of this repair is that it was free!
Plus it actually makes the lever work much better since it locks with the lever pulled in more so there is no clutch drag when pedaling.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.