Hi, my 2c about Shimano brifters: after a small laydown on the road (my mates are still laughing about my need for a good sleep) my left hand lever got un-responsive to the point where it wont release the gear cable when pressing the lever #2.
I have discovered that you can get the two levers to clash with their innermost faces one to each other, hence the lever #2 not returning in position. With the help of a flat screwdriver I was able to bend back the lever, thus having the required gap between the two.
It has been working well for the time being, fingers crossed it will hold even longer as I'm not in a rush to buy a new lever!
General cycling advice ( NOT technical ! )