Lazy left turn signal won't stay

[AnlaufJohn]

I think I am finally getting tired of pressing down on the lever for the left turn signal to stay engaged. Sometimes, it will stay, but most times it won't.
Now, let me be clear here: externally, the left rear light blinks, but the dash light doesn't blink, which means the front blinker doesn't blink.
This is a replacement turn signal switch I installed about 5 years ago, and it never seemed to bother me. Until this last week.
When I lift up on the lever to turn right, there is a positive step into the notch that keeps all the lights working, just as they should.
When I push the lever down, I don't get the same feeling, more like a sponge is blocking the switch from a positive engagement. If I put gentle downward pressure on the lever, all is well.
Another clue is if I am waiting to turn left, the lever may go and act correctly, with the dash light flashing. If I bump the steering wheel while reaching across to roll the window down, the dash light goes out and the front light doesn't work.
This has been its behavior the whole time. Any ideas of what is the problem?
I don't recall any broken pieces or difficulty in installing the t/s switch back then.
Many thanks,
John